Strategy-proofness

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 without advice stays at 20%, whereas the rate increases to 47% among those who have received advice. By conducting similar experiments for the pay-your-bid auction, which is not strategy-proof, we confirm that the increase in truth-telling is due significantly to the net advice effect (i.e., the effect beyond the so-called experimenter demand effect). Moreover, we find that providing advice improves efficiency in the Vickrey auction, particularly in the early periods, when the subjects are less experienced. In general, subjects tend to overbid in Vickrey auction experiments. Our results indicate the possibility that providing simple advice decreases such overbidding by promoting a better understanding of the strategy-proofness of the Vickrey auction. Strategy-proof mechanisms are sometimes criticized because players often fail to recognize the benefit of telling the truth. However, our observations show that introducing advice on the property of strategy-proofness helps them behave "correctly.

We consider situations where a society allocates a finite units of an indivisible good among agents, and each agent receives at most one unit of the good. For example, imagine that a government allocates a fixed number of licences to private firms, or imagine that a government distributes equally divided lands to households. We show that the Vickrey allocation rule is the unique allocation rule satisfying strategy-proofness, anonymity and individual rationality.

We study a class of preference domains that satisfies the familiar properties of minimal richness, diversity and no-restoration. We show that a specific preference restriction, hybridness, has been embedded in these domains so that the preferences are single-peaked at the "extremes" and unrestricted in the "middle". We also study the structure of strategy-proof and unanimous Random Social Choice Functions on these domains. We show them to be special cases of probabilistic fixed ballot rules (introduced by Ehlers, ).

Resumen: This paper introduces a property over agents' preferences, called Tops Responsiveness Condition. Such a property guarantees that the core in Hedonic Coalition Formation games is not empty. It is also shown that a mechanism exists that selects a stable allocation. It turns out that this mechanism, to be called tops covering, is strategy-proof even if the core is not a singleton. Furthermore, we also find out that the tops covering mechanism is the only strategy-proof mechanism that always selects stable allocations.

We study Random Social Choice Functions (or RSCFs) in a standard ordinal mechanism design model. We introduce a new preference domain called a hybrid domain which includes as special cases as the complete domain and the single-peaked domain. We characterize the class of unanimous and strategy-proof RSCFs on these domains and refer to them as Restricted Probabilistic Fixed Ballot Rules (or RPFBRs). These RSCFs are not necessarily decomposable, i.e., cannot be written as a convex combination of their deterministic counterparts. We identify a necessary and sufficient condition under which decomposability holds for anonymous RPFBRs. Finally, we provide an axiomatic justification of hybrid domains and show that every connected domain satisfying some mild conditions is a hybrid domain where the RPFBR characterization still prevails.

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We consider the problem of dividing one unit of an infinitely divisible object among a finite number of agents. We provide a characterization of all single-peaked domains on which the uniform rule is the unique division rule satisfying efficiency, strategy-proofness, and equal treatment of equals (ETE). We also provide a class of division rules satisfying these properties on the remaining single-peaked domains. Next, we consider non single-peaked domains and provide a characterization of all such domains on which the uniform rule satisfies efficiency, strategy-proofness, and ETE. We also show that under some mild richness conditions the uniform rule is the unique rule satisfying the mentioned properties on these domains. Finally, we provide a class of division rules satisfying efficiency, strategy-proofness, and ETE on the remaining non single-peaked domains. We conclude the paper by providing a wide range of applications to justify the usefulness of our results.

We consider the problem of dividing one unit of an infinitely divisible object amongst some agents. First, we provide all single-peaked domains where a division rule satisfies efficiency, strategy-proofness, and equal treatment of equals if and only if it is the uniform rule. Our characterisation depends on the number of agents. We also provide a class of division rules satisfying these properties on the domains on which the said characterization does not hold. Second, we consider domains that are not necessarily single-peaked and provide a characterization of maximal non-single-peaked domains on which a division rule satisfies efficiency, strategy-proofness, and equal treatment of equals if and only if it is the uniform rule. Third, we consider the case where the shares of the agents are bounded and provide a characterisation of the division rules on single-peaked domains satisfying efficiency, strategy-proofness, and equal treatment of equals. Finally, we drop the requirement of e...

Finitely many agents have preferences on a finite set of alternatives, single-peaked with respect to a connected graph with these alternatives as vertices. A probabilistic rule assigns to each preference profile a probability distribution over the alternatives. First, all unanimous and strategy-proof probabilistic rules are characterized when the graph is a tree. These rules are uniquely determined by their outcomes at those preference profiles at which all peaks are on leaves of the tree and, thus, extend the known case of a line graph. Second, it is shown that every unanimous and strategy-proof probabilistic rule is random dictatorial if and only if the graph has no leaves. Finally, the two results are combined to obtain a general characterization for every connected graph by using its block tree representation.

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or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User

We study Random Social Choice Functions (or RSCFs) in a standard ordinal mech-anism design model. We introduce a new preference domain called a hybrid domain which includes as special cases as the complete domain and the single-peaked domain. We characterize the class of unanimous and strategy-proof RSCFs on these domains and refer to them as Restricted Probabilistic Fixed Ballot Rules (or RPFBRs). These RSCFs are not necessarily decomposable, i.e., cannot be written as a convex combina-tion of their deterministic counterparts. We identify a necessary and sufficient condition under which decomposability holds for anonymous RPFBRs. Finally, we provide an axiomatic justification of hybrid domains and show that every connected domain satis-fying some mild conditions is a hybrid domain where the RPFBR characterization still prevails.

The concept lattice of a coalitional game form is introduced and advocated as a structural classificatory tool. The basic properties of such lattices are studied. Sufficient concept-latticial properties for convexity of the underlying coalitional game form are identified. Spectral issues concerning widths and lengths of concept lattices of convex CGFs are also addressed.

Y. Martinez, and E. Esteban. 2014. Social choice and groundwater management: application of the uniform rule. Cien. Inv. Agr. 41(2): 153-162. In recent decades, the protection of groundwater resources has become a key element in environmental policies around the world as the control of groundwater extraction is necessary to avoid groundwater depletion. This paper proposes a system to improve the allocation of groundwater resources based on the theory of social choice. We propose the implementation of the uniform rule as a mechanism to achieve more efficient groundwater allocation. The uniform rule combines individual preferences to reach collective decisions and respects the anonymity between agents. Additionally, the rule is Pareto efficient and strategy-proof. The paper compares the results obtained under the uniform rule with results achieved under other allocation rules: the proportional rule and the market rule. A numerical application is developed for the Western La Mancha aquifer (Spain), where intensive irrigated agriculture in recent decades has created serious overexploitation problems. The results highlight how the uniform rule is able to substantially improve the efficiency of groundwater extraction.

We consider the allocation problem of assigning heterogenous objects to a group of agents and determining how much they should pay. Each agent receives at most one object. Agents have non-quasi-linear preferences over bundles, each consisting of an object and a payment. Especially, we focus on the cases: (i) objects are linearly ranked, and as long as objects are equally priced, agents commonly prefer a higher ranked object to a lower ranked one, and (ii) objects are partitioned into several tiers, and as long as objects are equally priced, agents commonly prefer an object in the higher tier to an object in the lower tier. The minimum price rule assigns a minimum price (Walrasian) equilibrium to each preference pro…le. We establish: (i) on a common-object-ranking domain, the minimum price rule is the only rule satisfying e¢ ciency, strategy-proofness, individual rationality and no subsidy, and (ii) on a common-tiered-object domain, the minimum price rule is the only rule satisfying these four axioms.

Similar characterizations of Groves rules are previously established by Green and Laffont (1977), and Walker (1978). However, the characterizations of the these two articles cannot be applied to auction models since they assume that the class of admissible preferences include preferences which are not admissible in auction models. Makowski and Ostroy (1987) apply Holmstrom's (1979) result to more general model, and obtain similar conclusion when preferences are quasi-linear. Chew and Serizawa (2004) also characterize the Vickrey allocation rule in the auction model with quasi-linear domains by induction logic. 7 See Milgrom (2004) for the detailed explanation of Holmtrom's technique. 8 An allocation rule is a competitive allocation rule if the rule assigns to each preference profile a competitive equilibrium allocation for the profile.

We consider the multi-object allocation problem with monetary transfers where each agent obtains at most one object (unit-demand). We focus on allocation mechanisms satisfying individual rationality, non-wastefulness, equal treatment of equals, and strategy-proofness. Extending the result of Kazumura et al. (J Econ Theory 188:105036, 2020b), we show that for an arbitrary number of agents and objects, the minimum price Walrasian is the unique ex-post revenue maximizing mechanism among the mechanisms satisfying no subsidy in addition to the four properties, and that no subsidy in this result can be replaced by no bankruptcy on the positive income effect domain. We are grateful to two anonymous referees for their constructive comments. We also would like to thank Tomoya Kazumura, Debasis Mishra, Hiroki Shinozaki, Yu Zhou, and the participants of the 2nd ISI-ISER Young Economists Workshop and Nanjing-Osaka Economic Theory Workshop.

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We consider the economy consisting of n agents and m heterogenous objects where the seller benefits v from objects. Our study focuses on the multi-object allocation problem with monetary transfers where each agent obtains at most one object (unit-demand). In the situation with arbitrary n, m and v, we show that the minimum price Walrasian rule with reserve prices adjusted to v on the classical domain is the only rule satisfying four desirable properties; efficiency, strategyproofness, individual rationality and no-subsidy. Our result is an extension of that of Morimoto and Serizawa (2015), and so we can consider more general situation than them. Moreover, we characterize the minimum price Walrasian rules by efficiency, strategy-proofness and two-sided individual rationality.

We study the slot allocation problem where agents have quasi-linear single-peaked preferences over slots and identify the rules satisfying e¢ciency, strategy-proofness, and individual rationality. Since the quasi-linear single-peaked domain is not connected, the famous characterization of the Vickrey rule in terms of the three properties in Holmström (1979) cannot be applied. However, we are able to establish that on the quasi-linear singlepeaked domain, the Vickrey rule is still the only rule satisfying e¢ ciency, strategy-proofness, and individual rationality.

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 without advice stays at 20%, whereas the rate increases to 47% among those who have received advice. By conducting similar experiments for the pay-your-bid auction, which is not strategy-proof, we confirm that the increase in truth-telling is due significantly to the net advice effect (i.e., the effect beyond the so-called experimenter demand effect). Moreover, we find that providing advice improves efficiency in the Vickrey auction, particularly in the early periods, when the subjects are less experienced. In general, subjects tend to overbid in Vickrey auction experiments. Our results indicate the possibility that providing simple advice decreases such overbidding by promoting a better understanding of the strategy-proofness of the Vickrey auction. Strategy-proof mechanisms are sometimes criticized because players often fail to recognize the benefit of telling the truth. However, our observations show that introducing advice on the property of strategy-proofness helps them behave "correctly."

We consider the multi-object allocation problem with monetary transfers where each agent obtains at most one object (unit-demand). We focus on allocation rules satisfying individual rationality, no subsidy, efficiency, and strategy-proofness. Extending the result of Morimoto and Serizawa (2015), we show that for an arbitrary number of agents and objects, the minimum price Walrasian is characterized by the four properties on the classical domain.

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It is shown that simple and coalitional strategy-proofness of an aggregation rule on any rich weakly unimodal domain of a convex idempotent interval space are equivalent properties if that space satis…es interval anti-exchange, a basic property also shared by a large class of convex geometries including-but not reducing to-trees and Euclidean convex spaces. Therefore, strategy-proof location problems in a vast class of networks fall under the scope of that proposition. It is also established that a much weaker minimal anti-exchange property is necessary to ensure equivalence of simple and coalitional strategy-proofness in that setting. An immediate corollary to that result is that such equivalence fails to hold both in certan median interval spaces including those induced by bounded distributive lattices that are not chains, and in certain non-median interval spaces including those induced by partial cubes that are not trees. Thus, it turns out that anti-exchange properties of the relevant interval space provide a powerful general common principle that explains the varying relationship between simple and coalitional strategy-proofness of aggregation rules for rich weakly unimodal domains across di¤erent interval spaces, both median and non-median. MSC 2010 Classi…cation: 05C05, 52021, 52037 JEL Classi…cation number : D71 Acknowledgment: Thanks are due to two anonymous reviewers for their helpful comments and criticisms. The usual disclaimer applies.

People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:

A social choice function may or may not satisfy a desirable property depending on its domain of definition. For the same reason, different conditions may be equivalent for functions defined on some domains, while not in other cases. Understanding the role of domains is therefore a crucial issue in mechanism design. We illustrate this point by analyzing the role of two conditions, monotonicity and reshuffling invariance, that are always necessary, but not always sufficient for strategy-proofness. We identify domains, that we call intertwined, ensuring the equivalence between these two conditions and that of strategy-proofness for whatever functions are defined on them. We prove that some important domains are intertwined: those of single-peaked preferences, both with public and private goods, and also those arising in simple models of house allocation. We also discuss the relationship between our conditions on functions and domains with others considered in the literature.

Two distinct specifications of single peakedness as currently met in the relevant literature are singled out and discussed. Then, it is shown that, under both of those specifications, a voting rule as defined on a bounded distributive lattice is strategy-proof on the set of all profiles of single peaked total preorders if and only if it can be represented as an iterated median of projections and constants, or equivalently as the behaviour of a certain median tree-automaton. The equivalence of individual and coalitional strategy-proofness that is known to hold for single peaked domains in bounded linear orders fails in such a general setting. A related impossibility result on anonymous coalitionally strategy-proof voting rules is also obtained.

It is shown that, under a very comprehensive notion of single peakedness, an aggregation rule on a bounded distributive lattice is strategy-proof on any rich domain of single peaked total preorders if and only if it admits one of three distinct and mutually equivalent representations by lattice-polynomials, namely whenever it can be represented as a generalized weak consensus rule, a generalized weak sponsorship rule, or an iterated median rule. The equivalence of individual and coalitional strategy-proofness that is known to hold for single peaked domains in bounded linearly ordered sets and in …nite trees typically fails in such an extended setting. A related impossibility result concerning non-trivial anonymous and coalitionally strategy-proof aggregation rules is also obtained.

Two distinct specifications of single peakedness as currently met in the relevant literature are singled out and discussed. Then, it is shown that, under both of those specifications, a voting rule as defined on a bounded distributive lattice is strategy-proof on the set of all profiles of single peaked total preorders if and only if it can be represented as an iterated median of projections and constants, or equivalently as the behaviour of a certain median tree-automaton. The equivalence of individual and coalitional strategy-proofness that is known to hold for single peaked domains in bounded linear orders fails in such a general setting. A related impossibility result on anonymous coalitionally strategy-proof voting rules is also obtained.

It is shown that, under a very comprehensive notion of single peakedness, an aggregation rule on a bounded distributive lattice is strategy-proof on any rich domain of single peaked total preorders if and only if it admits one of three distinct and mutually equivalent representations by lattice-polynomials, namely whenever it can be represented as a generalized weak consensus rule, a generalized weak sponsorship rule, or an iterated median rule. The equivalence of individual and coalitional strategy-proofness that is known to hold for single peaked domains in bounded linearly ordered sets and in …nite trees typically fails in such an extended setting. A related impossibility result concerning non-trivial anonymous and coalitionally strategy-proof aggregation rules is also obtained.

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 …rst 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.

A collective decision problem is described by a set of agents, a profile of single-peaked preferences over the real line and a number k of public facilities to be located. We consider public facilities that do not suffer from congestion and are non-excludable. We provide a characterization of the class of rules satisfying Pareto-efficiency, object-population monotonicity and sovereignty. Each rule in the class is a priority rule that selects locations according to a predetermined priority ordering among "interest groups". We characterize each of the subclasses of priority rules that respectively satisfy anonymity, hiding-proofness and strategy-proofness. In particular, we prove that a priority rule is strategy-proof if and only if it partitions the set of agents into a fixed hierarchy. Alternatively, any such rule can be viewed as a collection of fixed-populations generalized peakselection median rules (Moulin, 1980), that are linked across populations, in a way that we describe.

Abstract: Abstract: We characterize the set of all individual and group strategy-proof rules on the domain of all single-dipped preferences on a line. For rules dened on this domain, and on several of its subdomains, we explore the implications of these strategy-proofness requirements on the maximum size of the rules' range. We show that when all singledipped preferences are admissible, the range must contain two alternatives at most. But this bound changes as we consider di¤erent subclasses of single-dipped preferences: we provide examples of subdomains admitting strategy-proof rules with larger ranges. We establish exact bounds on the maximal size of strategy-proof functions on each of these domains, and prove that the relationship between the sizes of the subdomains and those of the ranges of strategy-proof functions on them need not be monotonic. Our results exhibit a sharp contrast between the structure of strategy-proof rules defined on subdomains of single-dipped prefere...

We characterize the class of dominant-strategy incentive-compatible (or strategyproof) random social choice functions in the standard multi-dimensional voting model where voter preferences over the various dimensions (or components) are lexicographically separable. We show that these social choice functions (which we call generalized random dictatorships) are induced by probability distributions on voter sequences of length equal to the number of components. They induce a fixed probability distribution on the product set of voter peaks. The marginal probability distribution over every component is a random dictatorship. Our results generalize the classic random dictatorship result in Gibbard (1977) and the decomposability results for strategyproof deterministic social choice functions for multi-dimensional models with separable preferences obtained in LeBreton and Sen (1999). * We are particularly grateful to Huaxia Zeng for a careful reading of the paper and numerous helpful suggestions. We also thank a referee and the Editor for valuable comments. This research is supported by SMU Research Project 08-C244-SMU-014.

This note studies the allocation of heterogeneous commodities to agents whose private values for combinations of these commodities are monotonic by inclusion. This setting can accommodate the presence of complementarity and substitutability among the heterogeneous commodities. By using induction logic, we provide an elementary proof of Holmstrom's (1919) characterization of the Vickrey combinatorial auction as the unique efficient, strategy-proof, and individually rational allocation rule. Our proof method can also be applied to domains to which his proof cannot be.

We show that in general trading networks with bilateral contracts, a suitably adapted chain stability concept (Ostrovsky, 2008) is equivalent to stability (Hatfield and Kominers, 2012; Hatfield et al., 2013) if all agents' preferences are jointly fully substitutable and satisfy the Laws of Aggregate Supply and Demand. We also show that in the special case of trading networks with transferable utility, an outcome is consistent with competitive equilibrium if and only if it is not blocked by any chain of contracts. Moreover, from a computational perspective, checking whether an outcome is chain stable is substantially easier than directly checking whether an outcome is stable.

In many-to-one matching with contracts, agents on one side of the market, e.g., workers, can ful ll at most one contract, while agents on the other side of the market, e.g., rms, may desire multiple contracts. Hat eld and Milgrom [6] showed that when rms' preferences are substitutable and size monotonic, the worker-proposing cumulative o er mechanism is stable and strategy-proof (for workers). 1 Recently, stable and strategy-proof matching has been shown to be possible in a number of real-world se ings in which preferences are not necessarily substitutable (see, e.g., Sönmez and Switzer [13], Sönmez [12], Kamada and Kojima [7], and Aygün and Turhan [1]); this has motivated a search for weakened substitutability conditions that guarantee the existence of stable and strategy-proof mechanisms. Hat eld and Kojima [3] introduced unilateral substitutability and showed that when all rms' preferences are unilaterally substitutable (and size monotonic), the cumulative o er mechanism is stable and strategy-proof. Kominers and Sönmez [9] identi ed a novel class of preferences, called slot-speci c priorities, and showed that if each rm's preferences are in this class, then the cumulative o er mechanism is again stable and strategy-proof. Subsequently, Hat eld and Kominers [4] developed a concept of substitutable completion and showed that when each rm's preferences admit a size monotonic substitutable completion, the cumulative o er mechanism is once more stable and strategy-proof. In this paper, we introduce three novel conditions-observable substitutability, observable size monotonicity, and non-manipulability via contractual terms-and show that when these conditions are satis ed, the cumulative o er mechanism is the unique mechanism that is stable and strategy-proof. Moreover, when the choice function of any rm fails one of our three conditions, we can construct unit-demand choice functions for the other rms such that no stable and strategy-proof mechanism exists.

Various forms of substitutability are essential for establishing the existence of equilibria and other useful properties in diverse settings such as matching, auctions, and exchange economies with indivisible goods. We extend earlier models' definitions of substitutability to settings in which each agent can be both a buyer in some transactions and a seller in others, and show that all these definitions are equivalent. We then introduce a new class of substitutable preferences that allows us to model intermediaries with production capacity. We also prove that substitutability is preserved under economically important transformations such as trade endowments, mergers, and limited liability.

We develop a model of many-to-many matching with contracts that subsumes as special cases many-tomany matching markets and buyer-seller markets with heterogeneous and indivisible goods. In our setting, substitutable preferences are sufficient to guarantee the existence of stable outcomes; moreover, in contrast to results for the setting of many-to-one matching with contracts, if any agent's preferences are not substitutable, then the existence of a stable outcome cannot be guaranteed. In many-to-many matching with contracts, a new market design issue arises: The design of the contract language can impact the set of stable outcomes. Bundling contractual primitives encourages substitutability of agents' preferences over contracts and makes stable outcomes more likely to exist; however, bundling also makes the contractual language less expressive. Consequently, in choosing contract language, market designers face a tradeoff between expressiveness and stability.

We study the effect of different school choice mechanisms on schools' incentives for quality improvement. To do so, we introduce the following criterion: A mechanism respects improvements of school quality if each school becomes weakly better off whenever that school becomes more preferred by students. We first show that no stable mechanism, or mechanism that is Pareto efficient for students (such as the Boston and top trading cycles mechanisms), respects improvements of school quality. Nevertheless, for large school districts, we demonstrate that any stable mechanism approximately respects improvements of school quality; by contrast, the Boston and top trading cycles mechanisms fail to do so. Thus a stable mechanism may provide better incentives for schools to improve themselves than the Boston and top trading cycles mechanisms.

We consider the matching with contracts framework of Hatfield and Milgrom (2005), and we introduce new concepts of bilateral and unilateral substitutes. We show that bilateral substitutes is a sufficient condition for the existence of a stable allocation in this framework. However, the set of stable allocations does not form a lattice under this condition, and there does not necessarily exist a doctor-optimal stable allocation. Under a slightly stronger condition, unilateral substitutes, the set of stable allocations still does not necessarily form a lattice with respect to doctors' preferences, but there does exist a doctor-optimal stable allocation, and other key results such as incentive compatibility and the rural hospitals theorem are recovered.

Hatfield and Milgrom (2005) present a unified model of matching with contracts, which includes the standard two-sided matching and some package auction models as special cases. They show that the doctor-optimal stable mechanism is strategy-proof for doctors if hospitals' preferences satisfy substitutes and the law of aggregate demand. We show that the doctor-optimal stable mechanism is group strategy-proof for doctors under these same conditions. That is, no group of doctors can make each of its members strictly better off by jointly misreporting their preferences. We derive as a corollary of this result that no individually rational matching is preferred by all the doctors to the doctor-optimal stable match.

We provide an algorithm for testing the substitutability of a length-N preference relation over a set of contracts X in time O(|X| 3 • N 3). Access to the preference relation is essential for this result: We show that a substitutability-testing algorithm with access only to an agent's choice function must make an expected number of queries exponential in |X|. An analogous result obtains when the agent's preferences are quasilinear in a numeraire and the algorithm has access to the agent's underlying valuation function.

Y. Martinez, and E. Esteban. 2014. Social choice and groundwater management: application of the uniform rule. Cien. Inv. Agr. 41(2): 153-162. In recent decades, the protection of groundwater resources has become a key element in environmental policies around the world as the control of groundwater extraction is necessary to avoid groundwater depletion. This paper proposes a system to improve the allocation of groundwater resources based on the theory of social choice. We propose the implementation of the uniform rule as a mechanism to achieve more efficient groundwater allocation. The uniform rule combines individual preferences to reach collective decisions and respects the anonymity between agents. Additionally, the rule is Pareto efficient and strategy-proof. The paper compares the results obtained under the uniform rule with results achieved under other allocation rules: the proportional rule and the market rule. A numerical application is developed for the Western La Mancha aquifer (Spain), where intensive irrigated agriculture in recent decades has created serious overexploitation problems. The results highlight how the uniform rule is able to substantially improve the efficiency of groundwater extraction.

Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden. Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Terms of use: Documents in EconStor may be saved and copied for your personal and scholarly purposes. You are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public.

Centralized school admission mechanisms are an attractive way of improving social welfare and fairness in large educational systems. In this paper we report the design and implementation of the newly established school choice mechanism in Chile, where over 274,000 students applied to more than 6,400 schools. The Chilean system presents unprecedented design challenges that make it unique. On the one hand, it is a simultaneous nationwide system, making it one of the largest school admission problems worldwide. On the other hand, the system runs at all school levels, from Pre-K to 12th grade, raising at least two issues of outmost importance; namely, the system needs to guarantee their current seat to students applying for a school change, and the system has to favor the assignment of siblings to the same school. As in other systems around the world, we develop a model based on the celebrated Deferred Acceptance algorithm. The algorithm deals not only with the aforementioned issues, but also with further practical features such as soft-bounds and overlapping types. In this context we analyze new stability definitions, present the results of its implementation and conduct simulations showing the benefits of the innovations of the implemented system. CCS Concepts: • Theory of computation → Algorithmic mechanism design; • Applied computing → Economics.