Strategyproof Cost Sharing of Multiple Excludable Public Goods

In a model of cost sharing of multiple excludable public goods, we examine the properties of mechanisms satisfying strategyproofness, no subsidy, outcome non‐bossiness, budget balance, individual rationality and consumer sovereignty. We show that such mechanisms in general will not satisfy the equity property of equal treatment of equals. This contrasts with the single excludable public good case.     

Egalitarian division under Leontief Preferences

We consider the problem of fairly dividing $l$ divisible goods among $n$ agents with the generalized Leontief preferences. We propose and characterize the class of generalized egalitarian rules which satisfy efficiency, group strategy-proofness, anonymity, resource monotonicity, population monotonicity, envy-freeness and consistency. On the Leontief domain, our rules generalize the egalitarian-equivalent rules with reference bundles. We also extend our rules to agent-specific and endowment-specific egalitarian rules. The former is a larger class of rules satisfying all the previous properties except anonymity and envy-freeness. The latter is a class of efficient, group strategy-proof, anonymous and individually rational rules when the resources are assumed to be privately owned.     

Second-best efficiency of allocation rules: strategy-proofness and single-peaked preferences with multiple commodities

We study strategy-proof allocation rules in economies with perfectly divisible multiple commodities and single-peaked preferences. In this setup, it is known that the incompatibility among strategy-proofness, Pareto efficiency and non-dictatorship arises in contrast with the Sprumont (Econometrica 59:509–519, 1991) one commodity model. We first investigate the existence problem of strategy-proof and second-best efficient rules, where a strategy-proof rule is second-best efficient if it is not Pareto-dominated by any other strategy-proof rules. We show that there exists an egalitarian rational (consequently, non-dictatorial) strategy-proof rule satisfying second-best efficiency. Second, we give a new characterization of the generalized uniform rule with the second-best efficiency in two-agent case.     

A characterization of egalitarian equivalence

Summary Consider a solution (an allocation rule) for an economy which satisfies the following criteria: (1) Pareto efficiency, (2) monotonicity, in the sense that if the set of attainable allocations of the economy becomes larger then the solution makes no consumer worse-off, (3) a weak and primitive notion of fairness with respect to some commodity, say commodityh, in the sense that in an exchange economy in which the aggregate endowment consists only of commodityh, the solution is equal division. We show that in the class of economies which includes non-convex technologies the only such solution is egalitarian equivalence with respect to commodityh. It is also shown that this characterization of egalitarian equivalence holds in convex exchange economies if we add a weak version of a positive association requirement.We are grateful to William Thomson and three anonymous referees for extensive comments on an earlier version. We also acknowledge helpful comments of the participants of the Social Choice and Welfare Conference held in Caen, June 1992.     

The computational complexity of random serial dictatorship

In social choice settings with linear preferences, random dictatorship is known to be the only social decision scheme satisfying strategyproofness and ex post efficiency. When also allowing indifferences, random serial dictatorship (RSD) is a well-known generalization of random dictatorship that retains both properties. RSD has been particularly successful in the special domain of random assignment where indifferences are unavoidable. While executing RSD is obviously feasible, we show that computing the resulting probabilities is #P-complete, and thus intractable, both in the context of voting and assignment.     

Exchange in a general market with indivisible goods

We show how to restrict trades in exchange markets with heterogeneous indivisible goods so that the resulting restricted exchange markets, the fixed deal exchange markets, have a unique core allocation. Our results on fixed deal exchange markets generalize classical results on the Shapley-Scarf housing market, in which each agent owns one good only. Furthermore, we define the class of fixed deal exchange rules for general exchange markets, and prove that these are the only exchange rules that satisfy strategyproofness, individual rationality, and a weak form of efficiency.     

A simple random assignment problem with a unique solution

Summary. All agents have the same ordinal ranking over all objects, receiving no object (opting out) may be preferable to some objects, agents differ on which objects are worse than opting out, and the latter information is private. The Probabilistic Serial assignment, improves upon (in the Pareto sense) the Random Priority assignment, that randomly orders the agents and offers them successively the most valuable remaining object. We characterize Probabilistic Serial by efficiency in an ordinal sense, and envy-freeness. We characterize it also by ordinal efficiency, strategyproofness and equal treatment of equals. Received: October 5, 1999; revised version: December 20, 2000     

No-envy in queueing problems

We explore the implications of no-envy(Foley 1967) in the context of queueing problems. We identify an easy way of checking whether a rule satisfies efficiencyand no-envy. The existence of such a rule can easily be established. Next, we ask whether there is a rule satisfying efficiency and no-envytogether with an additional solidarity requirement how agents should be affected as a consequence of changes in the waiting costs. However, there is no rule satisfying efficiency, noenvy, and either one of two cost monotonicity axioms. To remedy the situation, we propose modifications of no-envy, adjusted no-envyand backward/forward no-envy. Finally, we discuss whether three fairness requirements, no-envy, the identical preferences lower bound, and egalitarian equivalence, are compatible in this context.     

Strategy-proof risk sharing

We consider risk sharing problems with a single good and a finite number of states. Agents have a common prior and their preferences are represented in the expected utility form and are risk averse. We study efficient and individually rational risk sharing rules satisfying strategy-proofness, the requirement that no one can ever benefit by misrepresenting his preference. When aggregate certainty holds, we show that “fixed price selections” from Walrasian correspondence are the only rules satisfying efficiency, individual rationality, and strategy-proofness. However, when aggregate uncertainty holds, we show that there exists no rule satisfying the three requirements. Moreover, in the two agents case, we show that dictatorial rules are the only efficient and strategy-proof rules. Dropping the common prior assumption in the model, we show that this assumption is necessary and sufficient for the existence of rules satisfying the three main requirements in the two agents and aggregate certainty case.     

Behavioral Mechanism Design

This paper studies the mechanism design problem for the class of Bayesian environments where agents do care for the well‐being of others. For these environments, we fully characterize interim efficient (IE) mechanisms and examine their properties. This set of mechanisms is compelling, since IE mechanisms are the best in the sense that there is no other mechanism which generates unanimous improvement. For public good environments, we show that these mechanisms produce public goods closer to the efficient level of production as the degree of altruism in the preferences increases. For private good environments, we show that altruistic agents trade more often than selfish agents.     

Strongly stable networks

We analyze the formation of networks among individuals. In particular, we examine the existence of networks that are stable against changes in links by any coalition of individuals. We show that to investigate the existence of such strongly stable networks one can restrict focus on a component-wise egalitarian allocation of value. We show that when such strongly stable networks exist they coincide with the set of efficient networks (those maximizing the total productive value). We show that the existence of strongly stable networks is equivalent to core existence in a derived cooperative game and use that result to characterize the class of value functions for which there exist strongly stable networks via a “top convexity” condition on the value function on networks. We also consider a variation on strong stability where players can make side payments, and examine situations where value functions may be non-anonymous—depending on player labels.     

The weak core of simple games with ordinal preferences: implementation in Nash equilibrium

In a simple game, coalitions belonging to a given class are “absolutely powerful” while others have no power. We attempt to make this distinction operational. Toward this end, we propose two axioms on social choice correspondences, Strong Non-Discrimination and Exclusion. Strong Non-Discrimination describes circumstances under which certain coalitions, the losing coalitions, have no influence over social choice. Exclusion requires that there are situations in which certain coalitions, the winning coalitions, can exercise their power. We show that the weak core correspondence is the minimal correspondence satisfying Maskin Monotonicity and Strong Non-Discrimination. We also show that the weak core is the unique correspondence satisfying Nash implementability, Strong Non-Discrimination, and Exclusion.     

PARETO EFFICIENCY AND WEIGHTED MAJORITY RULES

We consider the design of decision rules in an environment with two alternatives, independent private values and no monetary transfers. The utilitarian rule subject to incentive compatibility constraints is a weighted majority rule, where agents' weights correspond to expected gains given that their favorite alternative is chosen. It is shown that a rule is interim incentive efficient if and only if it is a weighted majority rule, and we characterize those weighted majority rules that are ex ante incentive efficient. We also discuss efficiency in the class of anonymous mechanisms and the stability of weighted majority rules.     

Income distributions and decomposable divergence measures

Inequality indices evaluate the divergence between the income distribution and the hypothetical situation where all individuals receive the mean income, and are unambiguously reduced by a Pigou–Dalton progressive transfer. This paper proposes a new approach to evaluate the divergence between any two income distributions, where the latter can be a reference distribution for the former. In the case where the reference distribution is perfectly egalitarian – and uniquely in this case – we assume that any progressive transfer reduces the divergence, and that the divergence can be additively separated into inequality and efficiency loss. We characterize the unique class of decomposable divergence measures consistent with these views. We derive the associated relative and absolute subclasses, and we illustrate the applicability of our results. This approach extends the generalized entropy studied in inequality measurement.     

Why do popular mechanisms lack efficiency in random environments?

We consider the problem of randomly assigning n indivisible objects to n agents. Recent research introduced a promising mechanism, the probabilistic serial that has superior efficiency properties than the most common real-life mechanism random priority. On the other hand, mechanisms based on Gale's celebrated top trading cycles method have long dominated the indivisible goods literature (with the exception of the present context) thanks to their outstanding efficiency features. We present an equivalence result between the three kinds of mechanisms, that may help better understand why efficiency differences among popular mechanisms might arise in random environments. This result also suggests that the probabilistic serial and the random priority mechanisms can be viewed as two top trading cycles based mechanisms that essentially differ in the initial conditions of the market before trading starts.     

Strategy-proof Location on a Network

We consider rules that choose a location on a graph (e.g. a road network) based on agents' single-peaked preferences. First, we characterize the class of strategy-proof, onto rules when the graph is a tree. Such a rule is based on a collection of generalized median voter rules (Moulin, 1980) satisfying a consistency condition. Second, we characterize such rules for graphs containing cycles. We show that while such a rule is not necessarily dictatorial, the existence of a cycle grants some agent an amount of decisive power, unlike the case of trees. Rules for this case can be described in terms of a subclass of such rules for trees. Journal of Economic Literature Classification Numbers: C72, D78.     

The Manipulability of Fair Solutions in Assignment of an Indivisible Object with Monetary Transfers

Public decision making often involves the problem of fairly assigning one indivisible object to agents with monetary transfers. An example is the choice of the location of a garbage incineration facility where the accepting district should receive fair compensations from other districts. In this problem, we show that for broad classes of solutions satisfying a welfare lower bound and an efficiency‐oriented condition, the set of equilibrium allocations in the manipulation game associated with a given solution coincides with the set of all envy‐free allocations. This generalizes Tadenuma and Thomson's equivalence result for a class of envy‐free solutions. Our result covers the Shapley value, which is not covered by Tadenuma and Thomson's result.     

THE ECONOMICS OF SOCIAL SENTIMENTS: THE CASE OF ENVY

The widespread externality produced by the sentiment of envy is modelled in this paper. We show its specific structural properties, the conditions of its existence, the various reasons for its normative relevance, the basic tool of its analysis ("envy-free preferences") and its crucial relation with the property of equality of liberty ("equity"). We then show that the envy externality respects the efficiency of classical allocative processes in the relevant conditions (competitive markets with not too unequal incomes, cases with indivisibilities, equal-freedom individual choices, etc.). We in particular derive conditions of consistency between efficiency and the vanishing of the envy externality, as well as the effects of actual envy on "divide and choose" processes, preferences to reassignment, multidimensional maximin, "egalitarian equivalence", degrees of envy in society and the rationality of choices.     

Notes on economic equality

In this paper we propose a simple definition of economic equality and characterize non- paternalist egalitarian preferences. We compare our definition to the ideas of envy and fairness and extend these ideas to the case of extended benevolent preferences. In productive economies efficiency and equality may conflict, just as do efficiency and the absence of envy. We suggest a feasible compromise in this case.     

Socialism and incentives: Developing a framework

This paper proposes a framework for comparative analysis of economic systems that is broad enough to encompass not only variants of socialism, but also laissez-faire and other cases. The two basic components of the framework deal with information and incentives. A central problem is that of designing an incentive-compatible, informationally decentralized mechanism satisfying the requirements of optimality and fairness. Recent results show that there are limitations on the design of such mechanisms; in particular, it may be impossible to avoid lowering the level of satisfaction of some members of society in order to achieve equity and efficiency. J. Comp. Econ., Sept. 1979, 3(3), pp. 207–216. University of Minnesota, Minneapolis, Minnesota 55455.