Efficient strategy-proof exchange and minimum consumption guarantees

For exchange economies with classical economic preferences, it is shown that any strategy-proof social choice function that selects Pareto optimal outcomes cannot guarantee everyone a consumption bundle bounded away from the origin. This result demonstrates that there is a fundamental conflict between efficiency and distributional goals in exchange economies if the social choice rule is required to be strategy-proof.     

Efficient strategy-proof allocation functions in linear production economies

Summary. In a linear production model, we characterize the class of efficient and strategy-proof allocation functions, and the class of efficient and coalition strategy-proof allocation functions. In the former class, requiring equal treatment of equals allows us to identify a unique allocation function. This function is also the unique member of the latter class which satisfies uniform treatment of uniforms. Received: July 10, 1997 / Revised version: November 24, 1997     

A leximin characterization of strategy-proof and non-resolute social choice procedures

Summary. We characterize strategy-proof social choice procedures when choice sets need not be singletons. Sets are compared by leximin. For a strategy-proof rule g, there is a positive integer k such that either (i) the choice sets g(r) for all profiles r have the same cardinality k and there is an individual i such that g(r) is the set of alternatives that are the k highest ranking in i's preference ordering, or (ii) all sets of cardinality 1 to k are chosen and there is a coalition L of cardinality k such that g(r) is the union of the tops for the individuals in L. There do not exist any strategy-proof rules such that the choice sets are all of cardinality to k where . Received: November 8, 1999; revised version: September 18, 2001     

The difference indifference makes in strategy-proof allocation of objects

We study problems of allocating objects among people. Some objects may be initially owned and the rest are unowned. Each person needs exactly one object and initially owns at most one object. We drop the common assumption of strict preferences. Without this assumption, it suffices to study problems where each person initially owns an object and every object is owned. For such problems, when preferences are strict, the “top trading cycles” algorithm provides the only rule that is efficient, strategy-proof, and individually rational Ma (1994) [1]. Our contribution is to generalize this algorithm to accommodate indifference without compromising on efficiency and incentives.     

A general impossibility result on strategy-proof social choice hyperfunctions

A social choice hyperfunction picks a non-empty set of alternatives at each admissible preference profile over sets of alternatives. We analyze the manipulability of social choice hyperfunctions. We identify a domain D^λ of lexicographic orderings which exhibits an impossibility of the Gibbard–Satterthwaite type. Moreover, this impossibility is inherited by all well-known superdomains of D^λ. As most of the standard extension axioms induce superdomains of D^λ while social choice correspondences are particular social choice hyperfunctions, we are able to generalize many impossibility results in the literature.     

The Pareto-dominant strategy-proof and fair rule for problems with indivisible goods

We study the problem of allocating a set of indivisible goods among a set of agents when monetary transfers are not allowed. We consider two interesting cases of this problem: (1) the supply of each object is exactly one; and (2) the supply of an object may be greater than one. Our central requirements are strategy-proofness and ex post fairness. We propose a particular rule satisfying strategy-proofness and no-envy (as well as equal treatment of equals). For the first case, it Pareto dominates any other rule satisfying strategy-proofness and equal treatment of equals. For the second case, it Pareto dominates any other rule satisfying strategy-proofness and no-envy.     

Characterizations of strategy-proof and fair mechanisms for allocating indivisible goods

We study the problem of allocating indivisible goods when monetary compensations are possible. First, we characterize the set of strategy-proof and envy-free mechanisms. Second, we identify the Pareto undominated subset in the set of strategy-proof and envy-free mechanisms. These characterizations can be interpreted as envy-free selections of Groves mechanisms.JEL Classification Numbers C72, D63, D71, D82I would like to thank Jun Matsuyama, Hervé Moulin, Satoko Okuyama, Takehiko Yamato, Naoki Yoshihara, an associate editor, two anonymous referees, and seminar participants at Rice University and Tokyo Institute of Technology for helpful suggestions and detailed comments. Research was partially supported by Grant-in-Aid for Scientific Research 17730126 of the Ministry of Education, Culture, Sports, Science and Technology in Japan.     

Secure implementation experiments: Do strategy-proof mechanisms really work?

Strategy-proofness, requiring that truth-telling is a dominant strategy, is a standard concept used in social choice theory. Saijo, Sjöström and Yamato [Saijo, T., Sjöström, T., Yamato, T., 2003. Secure implementation: Strategy-proof mechanisms reconsidered. Working paper 4-03-1. Department of Economics, Pennsylvania State University] argue that this concept has serious drawbacks. In particular, many strategy-proof mechanisms have a continuum of Nash equilibria, including equilibria other than dominant strategy equilibria. For only a subset of strategy-proof mechanisms do the set of Nash equilibria and the set of dominant strategy equilibria coincide. For example, this double coincidence occurs in the Groves mechanism when preferences are single-peaked. We report experiments using two strategy-proof mechanisms. One of them has a large number of Nash equilibria, but the other has a unique Nash equilibrium. We found clear differences in the rate of dominant strategy play between the two.     

Self-Selection Consistent Functions

This paper studies collective choice rules whose outcomes consist of a collection of simultaneous decisions, each one of which is the only concern of some group of individuals in society. The need for such rules arises in different contexts, including the establishment of jurisdictions, the location of multiple public facilities, or the election of representative committees. We define a notion of allocation consistency requiring that each partial aspect of the global decision taken by society as a whole should be ratified by the group of agents who are directly concerned with this particular aspect. We investigate the possibility of designing efficient allocation consistent rules. We also explore whether such rules may in addition respect the Condorcet criterion. Journal of Economic Literature Classification Numbers: D7, D71.     

Consistent probability attitudes

In this paper, the principle of meaningful measurement of probabilistic attitudes is revisited. A new principle of consistency in probability attitudes is proposed, which allows for the identification of decision weights completely separate from utility. In the familiar and elegant von Neuman–Morgenstern setup of decision under risk with given objective probabilities, it is shown that, in the presence of standard properties for preferences, adding the new consistency principle leads to rank-dependent utility.     

Consistent representative democracy

We study axioms which define “representative democracy” in an environment in which agents vote over a finite set of alternatives. We focus on a property that states that whether votes are aggregated directly or indirectly makes no difference. We call this property representative consistency. Representative consistency formalizes the idea that a voting rule should be immune to gerrymandering. We characterize the class of rules satisfying unanimity, anonymity, and representative consistency. We call these rules “partial priority rules.” A partial priority rule can be interpreted as a rule in which each agent can “veto” certain alternatives. We investigate the implications of imposing other axioms to the list specified above. We also study the partial priority rules in the context of specific economic models.     

Consistent House Allocation

In practice we often face the problem of assigning indivisible objects (e.g., schools, housing, jobs, offices) to agents (e.g., students, homeless, workers, professors) when monetary compensations are not possible. We show that a rule that satisfies consistency, strategy-proofness, and efficiency must be an efficient generalized priority rule; i.e., it must adapt to an acyclic priority structure, except – maybe – for up to three agents in each object’s priority ordering. We are grateful to the Editor and an anonymous referee for helpful comments and suggestions. L. Ehlers acknowledges financial support from the SSHRC (Canada)     

The strategy-proof provision of public goods under congestion and crowding preferences

We examine the strategy-proof provision of excludable public goods when agents care about the number of other consumers. We show that strategy-proof and efficient social choice functions satisfying an outsider independence condition must always assign a fixed number of consumers, regardless of individual desires to participate. A hierarchical rule selects participants and a generalized median rule selects the level of the public good. Under heterogeneity in agents’ views on the optimal number of consumers, strategy-proof, efficient, and outsider independent social choice functions are much more limited and in an important case must be dictatorial.     

Top dominance and the possibility of strategy-proof stable solutions to matching problems

Summary This paper explores the possibility of designing strategy-proof mechanisms yielding satisfactory solutions to the marriage and to the college admissions problem. Our first result is negative. We prove that no strategy-proof mechanism can always choose marriages that are individually rational and Pareto efficient. This strengthens a result by Roth (1982) showing that strategy-proof mechanisms cannot always select stable marriages. The result also applies, a fortiori, to college admissions. Since finding difficulties with strategy-proofness is quite an expected result, we then address a second question which is classical within the incentives literature. Are there restrictions on the preferences of agents under which strategy-proof and stable mechanisms do exist? We identify a nontrivial restriction on the domain of preferences, to be called top dominance, under which there exist strategy-proof and stable mechanisms for both types of matching problems. The mechanisms turn out to be exactly those that derive from the most classical algorithms in the literature; namely, the women's optimal, the men's optimal and the student's optimal. Finally, top dominance is shown to be essentially necessary, as well as sufficient, for the existence of strategy-proof stable matching mechanisms.This work is partially supported by grant PB 89-0294, from the Directión General de Investigatión Ciencia y Tecnología of the Spanish Ministerio de Educación y Ciencia. Salvador Barberà is also grateful to the Instituto de Estudios Fiscales. This research was initiated while both authors were visting GREMAQ, Université des Sciencies Sociales, Toulouse, whose hospitality is gratefully acknowledged. The paper extends results that were circulated as GREMAQ W.P. 91.22.232. We are grateful to Matthew Jackson and Marilda Sotomayor for their comments.     

An extreme point characterization of random strategy-proof social choice functions: The two alternative case

We show that every strategy-proof random social choice function is a convex combination of strategy-proof deterministic social choice functions in a two-alternative voting model. This completely characterizes all strategy-proof random social choice functions in this setting.     

Consistent planning under quasi-geometric discounting

We study properties of stationary Markov-perfect equilibria in a general model of intertemporal choice under quasi-geometric discounting. The dynamics generated by stationary Markov-perfect equilibria can be very complicated, even if the model satisfies strict convexity and smoothness properties and the decision maker is arbitrarily patient. If there exist multiple stationary Markov-perfect equilibria, then it is in general possible to construct infinitely many non-degenerate stationary sunspot equilibria as well.     

Consistent Planning Under Uncertain Lifetime

This paper considers the problem of intertemporal planning when changing tastes result in inconsistent plans. This problem has been considered in the literature under the assumption of a lifetime certainty. Some of the solutions proposed in the literature exhibit certain undesirable properties such as incoherence and lack of Pareto-optimality. This paper proposes a procedure for solving the intertemporal dilemma when lifetime is uncertain. The proposed solution is coherent and Pareto-optimal, and is, in fact, valid for the case of certain as well as uncertain lifetime. [020]     

Consistent planning with changing tastes

This paper proposes an approach to achieving a consistent consumption plan which is free of the shortcomings that characterize earlier proposals in the literature. Specifically, our consumption plan exists, is coherent, and most important, is Pareto-optimal.     

Consistent High-precision Volatility from High-frequency Data

Estimates of daily volatility are investigated. Realized volatility can be computed from returns observed over time intervals of different sizes. For simple statistical reasons, volatility estimators based on high-frequency returns have been proposed, but such estimators are found to be strongly biased as compared to volatilities of daily returns. This bias originates from microstructure effects in the price formation. For foreign exchange, the relevant microstructure effect is the incoherent price formation, which leads to a strong negative first-order autocorrelation ρ(1)≃40 per cent for tick-by-tick returns and to the volatility bias. On the basis of a simple theoretical model for foreign exchange data, the incoherent term can be filtered away from the tick-by-tick price series. With filtered prices, the daily volatility can be estimated using the information contained in high-frequency data, providing a high-precision measure of volatility at any time interval.
(J.E.L.: C13, C22, C81).     

The net effect of advice on strategy-proof mechanisms: an experiment for the Vickrey auction

Experimental Economics - We conduct laboratory experiments for the multi-unit Vickrey auction with and without advice to subjects on strategy-proofness. The rate of truth-telling among the subjects...