nash implementation a complete characterization the authors extend e maskin s results on nash implementation first they establish a condition that is both necessary and sufficient for nash implementability if there are three or more agents the case covered by maskin s sufficiency result second and more important they examine the two agent case for which there existed no general sufficiency results the two agent model is the leading case for applications to contracting and bargaining for this case too they establish a condition that is both necessary and sufficient the authors use their theorems to derive simpler sufficiency conditions that are applicable in a wide variety of economic environments copyright 1990 by the econometric society

implementing a surplus division rule we show that in the class of surplus division problems where the size of the surplus may be dependent on how it is shared the nash bargaining solution is the unique symmetric and nash implementable division rule d 2005 published by elsevier b v

testing alternative theories of the firm transaction cost knowledge based and measurement explanations for make or buy decisions in information services firms boundary choices have undergone careful examination in recent years particularly in information services while transaction cost economics provides a widely tested explanation for boundary choice more recent theoretical work advances competing knowledge based and measurement cost explanations similar to transaction cost economics these theories examine the impact of exchange attributes on the performance of markets and hierarchies as institutions of governance these theories however offer alternative attributes to those suggested by transaction cost economics or offer alternative mechanisms through which similar attributes influence make buy choices traditional empirical specifications of make buy models are unable to comparatively test among these alternative theories by developing and testing a model of comparative institutional performance rather than institutional choice we examine the degree of support for these competing explanations of boundary choice hypotheses are tested using data on the governance of nine information services at 152 companies our results suggest that a theory of the firm and a theory of boundary choice is likely to be complex requiring integration of transaction cost knowledge based and measurement reasoning 1998 john wiley sons ltd

contingent commodities and implementation abstract in this note we study the relevance of using contingent commodity allocations when states are not directly contractible in such a setting a contingent commodity allocation takes the form of a social choice function and the question is whether this function is implementable using only very mild assumptions on the rule for selecting contingent commodity allocations we derive a strong negative result which proves to be robust with respect to different solution concepts employed for implementation these findings have interesting implications for the interpretation of arrow debreu economies

whose opinion counts implementation by sortition abstract sortition is the process of selecting decision makers or senators by a lottery we introduce sortition in implementation theory by augmenting a mechanism with a kleroterion or lottery machine p that selects the senators an outcome is implemented after consulting only the opinions of the senators we call the corresponding notion of implementation as p implementation and provide necessary and sufficient conditions for p implementation our main result is that in economic environments every nash implementable social choice rule scr is also p implementable if p selects every quartet of players with positive probability and always selects at least three senators we apply this result to two kleroteria oligarchic democracy and random sampling in economic environments every nash implementable scr can be implemented by oligarchic democracy of three oligarchs in economic environments every nash implementable scr can be implemented by randomly selecting four senators

an impossibility result for virtual implementation with status quo in this paper virtual implementation is restricted to deliver on the equilibrium path either a socially optimal outcome or a status quo an outcome fixed for all preference profiles under such a restriction for any unanimous and implementable social choice function there is a dictator who obtains her most preferable outcome as long as all agents prefer this outcome to the status quo further restrictions on the lottery space and the range of social choice functions allow the dictator to impose her most preferred outcome even when other agents prefer the status quo to this outcome

a note on the individualistic foundations of the core in economies with asymmetric information abstract two foundations of the core are considered in the context of exchange economies the standard coalition based interpretation and one based on the individual profit seeking behaviour of agents the resulting core notions coincide in symmetric information economies but diverge when generalized to economies with asymmetric information

can the new forms of investment substitute for the old forms a transaction costs perspective this paper uses transaction costs theory is used to explain the features of the new contractual alternatives to foreign direct investment the new forms to assess their efficiency and to forecast their future development

incentives and implementation in marriage markets with externalities abstract we study the implementability of stable correspondences in marriage markets with externalities we prove that contrary to what happens in markets without externalities no stable revelation mechanism makes a dominant strategy for the agents on one side of the market to reveal their preferences however the stable correspondence is implementable in nash equilibrium

inefficiency of strategy proof rules for pure exchange economies abstract in his pioneering article in decision and organization c b mcguire and r radner eds pp 297 336 north holland amsterdam 1972 hurwicz establishes that there is no strategy proof pareto efficient and individually rational rule for pure exchange economies with two agents and two goods provided that the domain includes a sufficiently wide class of classical preferences in this article we extend his result to pure exchange economies with any finite number of agents and goods we establish that i there is no strategy proof pareto efficient and individually rational rule on the class of classical homothetic and smooth preferences and ii there is no strategy proof pareto efficient and symmetric rule on the same class of preferences journal of economic literature classification numbers d78 d71 c72

fair production and allocation of an excludable nonrival good we study fairness in economies with one private good and one partially excludable nonrival good a social ordering function determines for each profile of preferences an ordering of all conceivable allocations we propose the following free lunch aversion condition if the private good contributions of two agents consuming the same quantity of the nonrival good have opposite signs reducing that gap improves social welfare this condition combined with the more standard requirements of unanimous indifference and responsiveness delivers a form of welfare egalitarianism in which an agent s welfare at an allocation is measured by the quantity of the nonrival good that consumed at no cost would leave her indifferent to the bundle she is assigned

essential facility financing and market structure abstract the paper analyzes the funding of an infrastructure project when an incumbent operator has private information about market profitability and the regulator does not have access to taxpayers money an open access policy raises welfare but may make the project non viable since funding must be provided by operators capital contributions we characterize the optimal market structure the regulator can ask the incumbent to bear a higher share of investment cost if the latter insists on an exclusive use yet the incumbent is willing to pay more for exclusivity the higher the demand that is precisely when competition yields the highest benefits at the optimum the incumbent s information is not used to determine market structure we further investigate the implications of this basic result in a dynamic context we show that the monopoly franchise policy is time consistent while an open access policy is not we also demonstrate that a threat of regulatory capture creates an open access presumption last we show that when the decision involves multiple projects monopoly segments should cross subsidize open access ones

how to avoid transferring a valuable asset many mechanisms such as auctions efficiently allocate an asset to the firm which values it most highly but sometimes the asset s owner may benefit from the transfer only if the asset is not too valuable to potential buyers in this setting we examine the efficiency of mechanisms when the potential buyers have private information about the asset s value we show that rent seeking and lobbying rather than merely wasting resources can lead to allocations which are close to efficient

nash implementation of the nash bargaining solution using intuitive message spaces abstract we provide mechanisms for the nash implementation of the nash bargaining solution if the set of possible payoff allocations is unknown to the planner while the status quo is known agents report payoff regions compatible with the status quo we remark that message spaces can be further reduced

full implementation and belief restrictions we introduce a framework to study the problem of full implementation under general restrictions on agents beliefs which we call implementation first we provide a characterization of the properties of the mechanisms that achieve implementation these conditions relate the possibility of achieving full implementation to the strength of the strategic externalities induced by the mechanism we then study how to achieve full implementation via the design of simple transfer schemes in these context the general conditions for implementation suggest a simple design principle in which belief restrictions are used to weaken the strategic externalities induced by the baseline transfers of the belief free benchmark importantly our results require minimal information on agents beliefs which regard simple moments of the distribution of types these moment conditions arise naturally in applications and in practical problems of mechanism design

ambivalent investment and the hold up problem in this paper we add to the foundations of incomplete contracting literature we study the hold up problem with ambivalent investment where investment benefits the investing party if ex post the right decision is undertaken but harms the investing party if the wrong decision is made in this context we show that the power of contracts to provide investment incentives depends on three factors the commitment value of contracts the amount of quasirents that the investing party can expect in the case of out of contract renegotiation and the degree of ambivalence of investment first contracts provide first best investment incentives when parties can commit to a contract regardless of the type of investment second with sufficiently ambivalent investment if parties cannot commit not to renegotiate a contract and if the investing party s bargaining power is intermediate contracts cannot improve investment incentives above those provided by no contract in contrast a simple buyer or seller option contract is optimal when the investing party s bargaining power is extreme jel d23 k12 l22

nash implementation and uncertain renegotiation we study nash implementation when the outcomes of the mechanism can be renegotiated among the agents but the planner does not know the renegotiation function that they will use we characterize the social objectives that can be implemented in nash equilibrium when the same mechanism must work for every admissible renegotiation function and show the importance of allowing the planner to sometimes take away resources from the agents

maskin monotonicity and infinite individuals abstract this paper examines the logical relationship among maskin monotonicity independent person by person monotonicity independent weak monotonicity strategy proofness and coalitional strategy proofness in a society with infinite individuals

inducing truthful revelation of generator reliability abstract liberalised electricity markets often include a capacity remuneration mechanism to allow generation firms recover their fixed costs various de rating factors and or penalties have been incorporated into such mechanisms in order to reward the unit based on the contribution they make to system security which in turn depends on the unit s reliability however this reliability is known to the firm but not to the regulator we adopt a mechanism design approach for capacity payments based on a declaration by the firm of their reliability the mechanism scales payments and penalties according to this declared reliability such that the firm s profit maximising strategy is to truthfully reveal its reliability a stochastic mixed complementarity problem mcp is used to model the interactions between the firms and we apply this methodology to a test system using irish electricity market data truth telling is induced increasing the efficiency of capacity payments while eliminating the requirement for the regulator to allocate resources to discovering reliability

nash implementation in pure public good economies abstract i study nash implementation in a model of pure public good economies without the controversial no veto power condition i prove that any social choice correspondence that is monotonic and satisfies unanimity and minimal liberty can be implemented in nash equilibrium

vertical integration in the u s auto industry a note on the influence of transaction specific assets abstract recent refinements in the theory of the firm suggest that organization form may be sensitive not only to the degree to which assets are specific to a transaction but also to the type of capital employed this paper reports evidence regarding the relative influence of transaction specific investments in physical and human capital on the pattern of vertical integration using new data obtained directly from u s auto manufacturers the results support the proposition that investments in specialized technical know how have a stronger influence than those in specialized physical capital on the decision to integrate production within the firm

manipulation of preferences and relative utilitarianism abstract given n agents with who wish to divide m commodities consider the n person noncooperative game with strategies consisting of concave increasing utility functions and whose outcomes are the relative utilitarian solution any constrained equal income competitive equilibrium allocation for the true utilities is shown to ba a nash equilibrium outcome for the noncooperative game conditions are presented under which these are the only pure strategy equilibrium outcomes journal of economic literature classification numbers c72 c78 d71

let them cheat abstract we consider the problem of fairly allocating a bundle of infinitely divisible goods among a group of agents with classical preferences we propose to measure an agent s sacrifice at an allocation by the size of the set of feasible bundles that the agent prefers to her consumption as a solution we select the allocations at which sacrifices are equal across agents and this common sacrifice is minimal we then turn to the manipulability of this solution in the tradition of hurwicz 1972 we identify under some mild assumptions on preferences the equilibrium allocations of the manipulation game associated with this solution when all commodities are normal for each preference profile each equal division constrained walrasian allocation is an equilibrium allocation conversely each equilibrium allocation is equal division constrained walrasian furthermore we show that if normality of goods is dropped then equilibrium allocations may not be equal division constrained walrasian

implementation in economies with non convex production technologies unknown to the designer this paper deals with the problem of incentive mechanism design in non convex production economies when production sets and preferences both are unknown to the designer we consider nash implementation of loss free average cost marginal cost voluntary trading and quantity taking pricing equilibrium allocations in economies involving increasing returns to scale or more general types of non convexities the mechanisms presented in the paper are well behaved they are feasible continuous and use finite dimensional message spaces moreover the mechanisms work not only for three or more agents but also for two agent economies

the adoption of voluntary environmental management programs in mexico first movers as institutional entrepreneurs this article analyzes the adoption of voluntary environmental management programs by firms operating in mexico mexican firms can obtain national certification clean industry and or international certification iso 14001 based on institutional entrepreneurship theory we posit that the role played by first movers as institutional entrepreneurs is crucial if these programs are to become established with sufficient strength and appeal this understanding is especially important in an environment where more than one program can be adopted we tested several hypotheses on the behaviors of 1328 facilities operating in mexico half of which 664 had certified environmental management programs of the 664 certified facilities 217 were classified as early adopters three variables predicted the likelihood of a facility being an early adopter 1 connected to international market 2 in the maquila sector and 3 linked to an industry association that offers free resources

a natural mechanism to choose the deserving winner when the jury is made up of all contestants abstract we analyze the problem of a jury choosing the winner from a set of agents when the identity of the deserving winner is common knowledge amongst the jurors but each juror is biased in favor of one different agent we propose a simple and natural mechanism that implements the socially optimal rule the winner is the deserving winner in subgame perfect equilibria

subgame perfect implementation of bargaining solutions abstract this paper provides simple four stage game forms that fully implement a large class of two person bargaining solutions in subgame perfect equilibrium the solutions that can be implemented by our game forms are those that maximize a monotonic and quasi concave function of utilities after normalizing each agent s utility function so that the maximum utility is 1 and the utility of the disagreement outcome is 0 this class of solutions includes the nash kalai smorodinsky and relative utilitarian solutions the game forms have a structure of alternating offers and contain no integer device

a resource based theory of the firm knowledge versus opportunism this paper develops a resource based knowledge based theory of the firm its thesis is that the organizational mode through which individuals cooperate affects the knowledge they apply to business activity we focus on the polar cases of organization within a firm as compared to market contracting there will be a difference in the knowledge that is brought to bear and hence in joint productivity under the two options thus as compared to opportunism based transaction cost theory we advance a separate yet complementary answer to the question why do firms exist our aim is to develop an empirically relevant and complementary theory of why firms are formed a theory based on irreducible knowledge differences between individuals rather than the threat of purposeful cheating or withholding of information we assume limited cognitive abilities on the part of individuals bounded rationality and assume that opportunistic behavior will not occur the latter allows us to determine whether resource based

credible communication in dynastic government abstract this paper studies information disclosure in a model of dynastic government when information about past policy choices comes exclusively from the reports of previous administrations each administration has an incentive to choose its suboptimal one shot expenditure policy and then misrepresent its choice to its successor consequently it has been suggested that horizontal accountability i e a system of governance where auditing functions lie outside the executive branch can ensure credible disclosure of a government s activities this paper suggests a cautious approach to that view the baseline model examines the reporting incentives of an external auditor who can independently verify the information each period even with auditing credible disclosure is shown to be problematic various extensions to this baseline model are examined in one extension liberal i e those prefering larger government expenditures and conservative those prefering smaller expenditures regimes and auditors evolve over time it is shown that conservative liberal auditors are not credible when the current regime is also conservative liberal moreover because information transmission stops when the auditor s and the regime s biases coincide effective deterrents even in the good periods when the auditor s and the administration s biases differ are difficult to construct in all periods the equilibrium requirement of auditor neutrality constrains the dynamic incentives for efficient policy choices these constraints are shown to bind away from optimal policies in standard constructions of equilibrium various ways in which auditing protocols can overcome these problems are discussed

coordination and discrimination in contracting with externalities divide and conquer abstract the paper studies bilateral contracting between n agents and one principal whose trade with each agent generates externalities on other agents it examines the effects of prohibiting the principal from i coordinating agents on her preferred equilibrium and ii making different contracts available to different agents these effects depend on whether an agent is more or less eager to trade when others trade more the prohibitions reduce the aggregate trade in the former case and have little or no effect in the latter case the inefficiencies under different contracting regimes are linked to the sign of the relevant externalities and are shown to be typically reduced by both prohibitions

efficient repeated implementation this paper examines repeated implementation of a social choice function scf with innitely lived agents whose preferences are determined randomly in each period an scf is repeated implementable in nash equilibrium if there exists a sequence of possibly history dependent mechanisms such that i its nash equilibrium set is non empty and ii every nash equilibrium outcome corresponds to the desired social choice at every possible history of past play and realizations of uncertainty we show with minor qualications that in the complete information environment an scf is repeated implementable in nash equilibrium if and only if it is ecient we also discuss several extensions of our analysis including constructions employing only nite mechanisms

implementation in undominated strategies a look at bounded mechanisms this paper examines the impact of placing natural restrictions on the mechanisms considered for implementation problems it is shown that if all mechanisms are considered and preferences satisfy a basic condition then any social choice correspondence can be implemented in undominated strategies an example points out that the strength of this result derives from the use of mechanisms with questionable features in part of the message space the agent who announces the highest integer is rewarded this sort of tail chasing construction common in the constructive proofs of the literature is used to assure that undesired strategy combinations do not form an equilibrium if such mechanisms are ruled out then the social choice correspondences which can be implemented in undominated strategies satisfy an incentive compatibility type condition called strategy resistence for social choice functions this is equivalent to strategy proofness this contrast suggests that this issue should be examined as it applies to other solution concepts used in implementation theory the last portion of the paper begins to explore the issue as it relates to nash implementation and undominated nash implementation

using transaction cost economics to explain outsourcing of accounting this study explores whether smes involved in the outsourcing of accounting tasks differ in terms of transactional and personal ceo characteristics from others that perform the same tasks within the company we rely on the transaction cost economics tce model while controlling for age educational background and trust of the sme executive in the external accountant a survey was developed to investigate the outsourcing by belgian smes both of routine entry of invoices interim reporting and non routine period end accounting preparation of financial statements accounting tasks for the routine accounting tasks frequency was significantly associated with outsourcing meanwhile for non routine accounting tasks asset specificity and frequency were significantly associated high frequency tasks were associated with lower levels of outsourcing similarly higher asset specificity was associated with lower levels of outsourcing furthermore the educational background of the ceo as well as the ceo s level of trust in the external accountant was significantly associated with outsourcing confirming the upper echelon theory having a more educated ceo was associated with lower levels of outsourcing both for routine and non routine accounting tasks

the determinants of trust in supplier automaker relationships in the us japan and korea we examine the determinants of trust in 453 supplier automaker relationships in the us japan and korea we define trust and derive a model of its determinants drawing upon 1 an embeddedness relationship based perspective 2 a process based perspective and 3 an economic hostage based perspective our findings indicate strong support for the process based perspective in all countries embeddedness was only important in japan and the economic hostage based variable stock ownership was not important in any country

maskin monotonicity in economies with indivisible goods and money abstract we consider the problem of allocating indivisible objects with monetary transfers we show that any maskin monotonic allocation rule exhibits strong asymmetry in treating agents even on finitely restricted preference domains

complexity and repeated implementation this paper examines the problem of repeatedly implementing an ecient social choice function when the agents preferences evolve randomly we show that the freedom to set dierent mechanisms at dierent histories can give the planner an additional leverage to deter undesirable behavior even if the mechanisms are restricted to be simple and nite specically we construct a history dependent sequence of simple mechanisms such that with minor qualications every pure subgame perfect equilibrium delivers the correct social choice at every history while every mixed equilibrium is strictly pareto dominated more importantly when faced with agents with a preference for less complex strategies at the margin the ecient social choice function can be repeatedly implemented in subgame perfect equilibrium in pure or mixed strategies our results demonstrate a positive role for complexity considerations in mechanism design

delegated monitoring versus arm s length contracting abstract this paper analyzes the optimal organization of input suppliers in a procurement context we discuss when a top firm chooses to induce information sharing and active coordination between its suppliers consolidation rather than having them contract at arm s length delegation in designing the organization the firm anticipates that different supplier networks have different costs of inducing information revelation from suppliers when the cost of information sharing varies the optimal organization exhibits various discrete degrees of consolidation there is excessive arm s length contracting compared to the case where the top firm controls this organizational choice itself the paper offers also a methodology to study in a unified framework various organizational forms separately analyzed in the literature

sincere and sophisticated players in an equal income market abstract we study the simultaneous direct revelation mechanism associated with each equal income competitive social choice function in the allocation of objects and money among sincere and strategic agents strategic agents take advantage of sincere agents they non cooperatively coordinate on the equal income competitive allocations for the true preferences that are pareto undominated for them within the set of equal income competitive allocations sincere agents are protected to some extent however their welfare is usually above their maximin payoff

does relationship specific investment depend on asset ownership evidence from a natural experiment in the housing market the classic hold up model grossman and hart 1986 predicts that allocations of asset ownership which expose a party to expropriation reduce relationship specific investments by this party in the empirical context of t he housing market i show that the hold up model predicts more relationship specific investments such as bathroom renovations in owner occupied housing than in rental housing i confirm this prediction for the german housing market to ob tain an exogenous variation of asset home ownership i use the natural experiment of the german reunification under the communist regime ownership exist ed but was economically meaningless it was a quasi random by product of dwelling choice yet after reunification ownership unexpectedly reacquired legal fo rce

fair divisions as attracting nash equilibria of simple games abstract we give a mechanism fully implementing envy free divisions such that strategy spaces are symmetric the set of nash equilibria is a global attractor for the best reply dynamics as a byproduct undesired mixed strategy equilibria are weeded out by the adjustment process

implementation with partial provability we extend implementation theory by allowing the social choice function to depend on more than just the preferences of the agents and allowing agents to support their statements with hard evidence we show that a simple condition on evidence is necessary for the implementation of a social choice function f when the preferences of the agents are state independent and sufficient for implementation for any preferences including state dependent with at least three agents if the social planner can perform small monetary transfers beyond those called for by f if transfers can be large f can be implemented in a game with perfect information when there are at least two players under a boundedness assumption for both results transfers only occur out of equilibrium the use of evidence enables implementation which is robust in the sense that the planner needs little information about agents preferences or beliefs and agents need little information about each others preferences our results are robust to evidence forgery at any strictly positive cost

an experiment on nash implementation we perform an experimental test of a modification of the controversial canonical mechanism for nash implementation using three subjects in non repeated groups as well as three outcomes states of nature and integer choices we find that this mechanism successfully implements the desired outcome a large majority of the time providing empirical evidence for the feasibility of such implementation in addition the performance is further improved by imposing a fine on a dissident so that the mechanism implements strict nash equilibria while our environment is stylized our results offer hope that experiments can identify reasonable features for practical implementation mechanisms

profitability transactional alignment and organizational mortality in the u s trucking industry the winds of creative destruction rarely blow more fiercely than in a newly deregulated environment managers simultaneously face a novel focus on operating efficiency and an onslaught of new competitors what must managers do to enable their firms to survive in such an environment what factors bear on firms survival this paper presents an analysis of mortality of large motor carriers in the u s interstate for hire trucking industry after deregulation it examines this phenomenon through a multidisciplinary lens that encompasses organizational ecology neoclassical economics and transaction cost economics the paper posits that carrier mortality is a function of both firm level and industry level attributes which are drawn from both ecological and economic theories while each of these theories separately informs motor carrier mortality the inclusion of predictions derived from both disciplines in one model significantly increases explanatory power over either theory evaluated alone the empirical analysis is among the first to show increased mortality when firms do not adhere to operating policies consistent with transaction cost minimization principles in sum managers are well advised to adopt a multidisciplinary approach to strategy to ensure their firms survival 1997 by john wiley sons ltd

characterizations of strategy proof mechanisms for excludable versus nonexcludable public projects first we characterize the unanimous mechanisms as the set of strategy proof individually rational and citizen sovereign mechanisms for the provision of a nonexcludable public project second we characterize the largest unanimous mechanisms as the set of strategy proof individually rational demand monotonic and access independent mechanisms for the provision of an excludable public project comparing these two classes of mechanisms we conclude that admitting partial exclusion always improves efficiency under the incentive compatibility constraint journal of economic literature classification numbers d71 d82 h41

preference domains and the monotonicity of condorcet extensions an alternative is a condorcet winner if it beats all other alternatives in a pairwise majority vote a social choice correspondence is a condorcet extension if it selects the condorcet winners and nothing else whenever a condorcet winner exists it is well known that condorcet extensions are not monotonic hence not nash implementable when all preferences are admissible but are implementable when restricted to a domain in which condorcet winners always exist we fill the gap by studying the intermediate domains and find that monotonicity is violated on all such domains

modes of foreign entry a transaction cost analysis and propositions a frontier issue in international marketing is the appropriate choice of entry mode in foreign markets the objective of this paper is to offer a transaction cost framework for investigating the entry mode decision this framework provides 1 a theoretical basis for systematically interrelating the literature into propositions 2 propositions about interactions which resolve the apparently contradictory arguments advanced to date specifically the paper illustrates the feasibility of clustering 17 entry modes into the degree of control the mode provides the entrant proposes that the most appropriate i e most efficient entry mode is a function of the tradeoff between control and the cost of resource commitment advances testable propositions delimiting the circumstances under which each mode maximizes long term efficiency

nash equilibrium and welfare optimality if is a set of social alternatives a social choice rule scr assigns a subset of a to each potential profile of individuals preferences over a where the subset is interpreted as the set of welfare optima a game form or mechanism implements the social choice rule if for any potential profile of preferences 1 any welfare optimum can arise as a nash equilibrium of the game form implying in particular that a nash equilibrium exists and 2 all nash equilibria are welfare optimal the main result of this paper establishes that any scr that satisfies two properties monotonicity and no veto power can be implemented by a game form if there are three or more individuals the proof is constructive

implementation in minimax regret equilibrium this note studies the problem of implementing social choice correspondences in environments where individuals have doubts about the rationality of their opponents we postulate the concept of minimax regret as our solution concept and show that social choice correspondences that are maskin monotonic and satisfy the no veto power condition are implementable in minimax regret equilibrium for all 0 1

a difficulty in implementing correlated equilibrium distributions we view achieving a particular correlated equilibrium distribution for a normal form game as an implementation problem we show using a parametric version of the two person chicken game that a social choice function that chooses any particular correlated equilibrium distribution does not satisfy maskin monotonicity and therefore can not be fully implemented in nash equilibrium thus no mechanism that aims to understand a correlated distribution as the unique outcome of nash equilibrium play can be found jel classi cation numbers c72 keywords correlated equilibrium distribution implementation monotonicity