perfect foresight and equilibrium selection in symmetric potential games the equilibrium selection approach of matsui and matsuyama j econ theory65 1995 415 434 which is based on rational players who maximize their discounted future payoff is analyzed for symmetric two player games with a potential function it is shown that the maximizer of the potential function is the unique state that is absorbing and globally accessible for small discount rates journal of economic literatureclassification number c72

on the robustness of equilibrium refinements abstract the philosophy of equilibrium refinements is that the analyst if he knows things about the structure of the game can reject some nash equilibria as unreasonable the word know in the preceding sentence deserves special emphasis if in a fixed game the analyst can reject a particular equilibrium outcome but he cannot do so for games arbitrarily close by then he may have second thoughts about rejecting the outcome we consider several notions of distance between games and we characterize their implications for the robustness of equilibrium refinements

stochastic stability in a double auction abstract in a k double auction a buyer and a seller must simultaneously announce a bid and an ask price respectively exchange of the indivisible good takes place if and only if the bid is at least as high as the ask the trading price being the bid price with probability k and the ask price with probability 1 k we show that the stable equilibria of a complete information k double approximate an asymmetric nash bargaining solution with the seller s bargaining power decreasing in k note that ceteris paribus the payoffs of the seller of the one shot game increase in k nevertheless as the stochastically stable equilibrium price decreases in k choosing the seller s favorite price with a relatively higher probability in individual encounters makes him worse off in the long run

optimal fiscal policy under multiple equilibria abstract we study optimal fiscal policy in an economy where i search frictions create a coordination problem and generate multiple pareto ranked equilibria and ii the government finances the provision of a public good by taxing market activity the government must choose the tax rate before it knows which equilibrium will obtain and therefore an important part of the problem is determining how the policy will affect the equilibrium selection process we show that when the equilibrium selection rule is based on the concept of risk dominance higher tax rates make coordination on the pareto superior outcome less likely as a result taking equilibrium selection effects into account leads to a lower optimal tax rate

industrialization under perfect foresight a world economy with a continuum of countries abstract a dynamic model of international trade with a continuum of countries is presented the terms of trade path each country takes as given are endogenous in the model countries differ by the rate of time preference and have populations of overlapping generations of labor industrialization is modeled as the reallocation of labor to the sector with external increasing returns the process of which is gradual due to a demographic constraint in a perfect foresight equilibrium countries with lower time preference industrialize and autarky policy is not effective for industrialization orbits may exist for countries with positive time preference journal of economic literature classification numbers d90 f10 f43 o14 o40

models of currency crises with self fulfilling features the discomfort a government suffers from speculation against its currency determines the strategic incentives of speculators and the scope for multiple currency market equilibria after describing an illustrative model in which high unemployment may cause an exchange rate crisis with self fulfilling features the paper reviews some other self reinforcing mechanisms recent econometric evidence seems consistent with the practical importance of these mechanisms

global analysis of an expectations augmented evolutionary dynamics we consider a deterministic evolutionary model where players form expectations about future play players are not fully rational and have expectations that change over time in response to current payoffs and feedback from the past we provide a complete characterization of the qualitative dynamics so induced for a two strategy population game and relate our findings to standard evolutionary dynamics and equilibrium selection when agents have rational forward looking expectations

subsidies to new energy sources do they add to energy stocks energy production subsidies are paradoxically shown to be likely to increase u s dependence on imported oil standard studies of net energy yields are shown to be seriously biased upward for two reasons first many omit indirect energy inputs which our input output calculation shows probably causes large errors second those studies all omit the energy opportunity costs of nonenergy inputs e g the fuel substituted elsewhere for the labor used to produce energy we prove that absent externalities any fuel output subsidy which causes an otherwise unprofitable expansion must yield an incremental fuel output smaller than the increment in energy input plus the energy opportunity costs of other inputs

unique equilibrium in a model of self fulfilling currency attacks even though self fulfilling currency attacks lead to multiple equilibria when fundamentals are common knowledge we demonstrate the uniqueness of equilibrium when speculators face a small amount of noise in their signals about the fundamentals this unique equilibrium depends not only on the fundamentals but also on financial variables such as the quantity of hot money in circulation and the costs of speculative trading in contrast to multiple equilibrium models our model allows analysis of policy proposals directed at curtailing currency attacks

stochastic stability in asymmetric binary choice coordination games abstract a recent literature in evolutionary game theory is devoted to the question of robust equilibrium selection under noisy best response dynamics in this paper we present a complete picture of equilibrium selection for asymmetric binary choice coordination games in the small noise limit we achieve this by transforming the stochastic stability analysis into an optimal control problem which can be solved analytically this approach allows us to obtain precise and clean equilibrium selection results for all canonical noisy best response dynamics which have been proposed so far in the literature among which we find the best response with mutations dynamics the logit dynamics and the probit dynamics

who matters in coordination problems we consider a common investment project that is vulnerable to a self fullling coordination failure and hence is strategically risky based on their private information agents who have heterogeneous investment incentives form expectations or sentiments about the project s outcome we nd that the sum of these sentiments is constant across dierent strategy proles and it is independent of the distribution of incentives as a result we can think of sentiment as a scarce resource divided up among the dierent payo types applying this nding we show that agents who benet little from the project s success have a large impact on the coordination process the agents with small benets invest only if their sentiment towards the project is large per unit investment cost as the average sentiment is constant a subsidy decreasing the investment costs of these agents will free up a large amount of sentiment provoking a large impact on the whole economy intuitively these agents insensitive to the project s outcome and hence to the actions of others are inuential because they modify their

optimal design of social comparison effects setting reference groups and reference points in this paper we study how social planners should exploit social comparisons to pursue their objectives we consider two modes of social comparison referred to as behind averse and ahead seeking behaviors depending on whether individuals experience a utility loss from underperforming or a utility gain from overperforming relative to their peers modeling social comparison as a game between players we find that ahead seeking behavior leads to output polarization whereas behind averse behavior leads to output clustering a social planner can mitigate these effects in two ways i by providing the full reference distribution of outputs instead of an aggregate reference point based on the average output and ii by assigning players into uniform rather than diverse reference groups social planners may thus need to tailor the reference structure to the predominant mode of social comparison and their objective a performance focused social planner may set the reference structure so as to maximize the output of either the top or the bottom player depending on whether she puts greater marginal weight to larger or smaller outputs when the social planner also cares about utility she faces a dilemma because performance optimization may not be aligned with utility maximization inevitably the social planner will have to confront equity issues because better performance may not reflect greater effort or greater ability this paper was accepted by serguei netessine operations management

bandwagon effects and long run technology choice abstract we introduce a class of bandwagon games which generalizes the notion of network externalities when there are more than two competing technologies and various degrees of partial compatibilities among them we then apply the stochastic evolutionary approach to this class of games we determine the conditions under which a globally pairwise risk dominant technology is the long run equilibrium lre we also show the conditions under which one technology takes over another technology by directly switching consumers from the latter to the former also called direct domination parametric examples illustrate the properties of the technology which is the lre journal of economic literature classification numbers c72 c73

the robustness of equilibria to incomplete information a number of papers have shown that a strict nash equilibrium action profile of a game may never be played if there is a small amount of incomplete information see for example carlsson and van damme 1993a we present a general approach to analyzing the robustness of equilibria to a small amount of incomplete information a nash equilibrium of a complete information game is said to be robust to incomplete information if every incomplete information game with payoffs almost always given by the complete information game has an equilibrium which generates behavior close to the nash equilibrium we show that many games with strict equilibria have no robust equilibrium and examine why we get such different results from existing refinements if a game has a unique correlated equilibrium it is robust a natural many player many action generalization of risk dominance is a sufficient condition for robustness

equilibrium selection inn person coordination games abstract this paper investigates several approaches to equilibrium selection and the relationships between them the class of games we study are n person generalized coordination games with multiple pareto rankable strict nash equilibria the main result is that all selection criteria select the same outcome namely the risk dominant equilibrium in two person games and that most equivalences break for games with more than two players all criteria select the pareto efficient equilibrium in voting games of which pure coordination games are special cases journal of economic literature classification numbers c70 c72 d82

correlated equilibrium as an expression of bayesian rationality if it is common knowledge that the players in a game are bayesian utility maximizers who treat uncertainty about other players actions like any other uncertainty then the outcome is necessarily a correlated equilibrium random strategies appear as an expression of each player s uncertainty about what the others will do not as the result of willful randomization use is made of the common prior assumption according to which differences in probability assessments by different individuals are due to the different information that they have where information may be interpreted broadly to include experience upbringing and genetic makeup copyright 1987 by the econometric society

international cartel enforcement lessons from the 1990s the enforcement record of the 1990s shows that private international cartels are not defunct nor do they always fall quickly under the weight of their own incentive problems of a sample of 40 such cartels prosecuted by the united states and the european union in the 1990s 24 lasted at least four years and for the 20 cartels in this sample where sales data are available the annual worldwide turnover in affected products exceeded 30 billion national competition policies address harm in domestic markets and in some cases prohibit cartels without taking strong enforcement measures the authors propose a series of reforms to national policies and steps to enhance international cooperation that will strengthen the deterrents against international cartelization furthermore the authors argue that aggressive prosecution of cartels must be complemented by vigilance in other areas of competition policy if not firms will respond to the enhanced deterrents to cartelization by merging or by taking other measures that lessen competitive pressures

rationalizable strategic behavior the notion of equilibrium proposed by nash 19 has come to play a dominant role in economic applications of noncooperative games while analyses of nash equilibria have unquestionably contributed to our understanding of economic behavior it would be unreasonably optimistic to maintain that nash solved the problem of noncooperative strategic choice there is a small literature beginning with ellsberg 6 and a much larger oral tradition which argues that nash behavior is neither a necessary consequence of rationality nor a reasonable empirical proposition in this paper i take the view that although there may be various reasons why an agent might select a nash strategy the notion of an equilibrium has little intrinsic appeal within a strategic context when an agent reaches a decision in ignorance of the strategies adopted by other players rationality consists of making a choice which is justifiable by an internally consistent system of beliefs rather than one which is optimal post hoc this point of view is not original indeed most serious justifications of the nash hypothesis embrace such an approach arguing that agents will expect the game to yield a nash outcome and consequently will choose their equilibrium strategies nevertheless when we think in terms of maximizing utility subject to expectations rather than realizations it becomes clear that the nash hypothesis far from being a consequence of rationality arises from certain restrictions on agents expectations which may or may not be plausible depending upon the game being played we are then quite naturally led to ask are there any restrictions of individuals expectations and hence choices which are required by rationality alone rather than by subjective plausibility this paper is concerned with defining justifying characterizing and refining a criterion for rational strategic choice which i label rationalizability

is ambiguity aversion bad for innovation abstract not necessarily i consider two firms that compete both on the research market and on the product market assuming the product market outcome is ambiguous i e uncertainty is described by multiple distribution of outcomes i show that an increase in firms ambiguity aversion increases the ex ante likelihood that they invest in r d an increase in their risk aversion on the other hand decreases innovation the result holds when the innovation has a business stealing effect as in a cournot duopoly with vertical differentiation the key intuition is that ambiguity aversion exacerbates the competitive threat whereas risk aversion diminishes the profit incentive to invest in addition to showing that an increase in ambiguity aversion leads to more projects being pursued i show that an increase in ambiguity aversion can lead to an increase in investment for incremental projects in the case of more radical projects an increase in ambiguity aversion can but not necessarily lead to lower investment in equilibrium overall ambiguity aversion has a positive effect on most innovative projects but can sometimes have a negative effect on some of the more radical game changing ones

efficiency and the role of government in energy policy abstract it is well established that the presence of a monopolist producer removes efficiency from the world oil market efficiency in energy resource utilization can nevertheless be the proclaimed objective of an energy policy by an oil importing nation if imported oil is considered a non produced resource available at a given price this article presents an example of such a policy which consists of the institution of price guarantees for energy alternatives and of government subsidies for the development of new energy technologies we illustrate how this policy will attain efficiency and the ratio of benefits to the costs associated with its adoption are calculated

what determines cartel success following george stigler 1964 many economists assume that incentive problems undermine attempts by firms to collude to raise prices and restrict output but the potential profits from collusion can create a powerful incentive as well theory cannot tell us a priori which effect will dominate whether or when cartels succeed is thus an empirical question we examine a wide variety of empirical studies of cartels to answer the following questions 1 can cartels succeed 2 if so for how long 3 what impact do cartels have 4 what causes cartels to break up we conclude that many cartels do survive and that the distribution of duration is bimodal while the average duration of cartels across a range of studies is about five years many cartels break up very quickly i e in less than a year but there are many others that last between five and ten years and some that last decades limited evidence suggests that cartels are able to increase prices and profits to varying degrees cartels can also affect other non price variables including advertising innovation investment barriers to entry and concentration cartels break up occasionally because of cheating or lack of effective monitoring but the biggest challenges cartels face are entry and adjustment of the collusive agreement in response to changing economic conditions cartels that develop organizational structures that allow them the flexibility to respond to these changing conditions are more likely to survive price wars that erupt are often the result of bargaining issues that arise in such circumstances sophisticated cartel organizations are also able to develop multipronged strategies to monitor one another to deter cheating and a variety of interventions to increase barriers to entry

rationalizable strategic behavior and the problem of perfection this paper explores the fundamental problem of what can be inferred about the outcome of a noncooperative game from the rationality of the players and from the information they possess the answer is summarized in a solution concept called rationalizability strategy profiles that are rationalizable are not always nash equilibria conversely the information in an extensive form game often allows certain unreasonable nash equilibria to be excluded from the set of rationalizable profiles a stronger form of rationalizability is appropriate if players are known to be not merely rational but also cautious what constitutes rational behavior in a noncooperative strategic situation this paper explores the issue in the context of a wide class of finite noncooperative games in extensive form the traditional answer relies heavily upon the idea of nash equilibrium nash 17 the position developed here however is that as a criterion for judging a profile of strategies to be reasonable choices for players in a game the nash equilibrium property is neither necessary nor sufficient some nash equilibria are intuitively unreasonable and not all reasonable strategy profiles are nash equilibria the fact that a nash equilibrium can be intuitively unattractive is well known the equilibrium may be imperfect introduced into the literature by selten 20 the idea of imperfect equilibria has prompted game theorists to search for a narrower definition of equilibrium while this research some of which will be discussed here has been extremely instructive it remains inconclusive theorists often agree about what should happen in particular games but to capture this intuition in a general solution concept has proved to be very difficult if this paper is successful it should make some progress in that direction the other side of the coin has received less scrutiny can all non nash profiles really be excluded on logical grounds i believe not the standard justifications for considering only nash profiles are circular in nature or make gratuitous assumptions about players decision criteria or beliefs the following discussion of these points is extremely brief due to space constraints more detailed arguments may be found in pearce 18

when are cartels stable contracts why do some industry cartels survive for decades while others are quickly undermined by price wars and entry variation in cartels longevity can be explained by differences in their costs of self enforcement and service value to members analyzing legal cartel contracts formed under the webb pomerene export trade act i find that longer lived cartels tended to export to small buyers to have wide industry coverage to operate in periods of stable prices and growing demand and to sell under side agreements with foreign competitors contracts in which the cartel centralized its control through a common sales agency tended to be more stable however cartels usually grew less stable with age and when there was a recent and long history of cartelization in the industry finally cartels whose primary rationale was to fix price tended to be particularly unstable because these contracts invited fringe competition and entry

correlated equilibrium in games with type dependent strategies abstract this paper extends aumann s definition of correlated equilibrium to games with incomplete information a strategy correlated equilibrium is defined to be a correlated equilibrium of the game in behavioral strategies it is shown that this equilibrium concept is robust with respect to misspecifications of the uncertainty in the game and the equilibrium correspondence is upperhemicontinuous with respect to the players payoff functions and information this implies the existence of strategy correlated equilibria without assumptions on the structure of players information none of these results have been proven for bayesian nash equilibria

p dominance and equilibrium selection under perfect foresight dynamics this paper studies equilibrium selection based on a class of perfect foresight dynamics and relates it to the notion of p dominance a continuum of rational players are repeatedly and randomly matched to play a symmetric n n game there are frictions opportunities to revise actions follow independent poisson processes the dynamics has stationary states each of which corresponds to a nash equilibrium of the static game a strict nash equilibrium is linearly stable under the perfect foresight dynamics if independently of the current action distribution there exists a consistent belief that any player necessarily plays the nash equilibrium action at every revision opportunity it is shown that a strict nash equilibrium is linearly stable under the perfect foresight dynamics with a small degree of friction if and only if it is the p dominant equilibrium with p 1 2 it is also shown that if a strict nash equilibrium is the p dominant equilibrium with p 1 2 then it is uniquely absorbing and globally accessible for a small friction but not vice versa set valued stability concepts are introduced and their existence is shown journal of economic literature classication numbers c72 c73

optimal subsidies to new energy sources abstract this paper broadens previous discussion on the conditions for subsidizing new energy sources several arguments for and against subsidizing new energy sources such as solar energy and synthetic fuels are reviewed and critiqued emphasis is given to vintage subsidies to conventional energy sources net energy analysis and a variety of production externalities a theorem for determining optimal subsidies to new energy sources is developed based on a general theorem proposed by baumol and bradford 2 finally two equity issues are also considered

incomplete information higher order beliefs and price inertia the question that motivates this paper is how incomplete information impacts the response of prices to nominal shocks our baseline model is a variant of the calvo model in which firms observe the underlying nominal shocks with noise in this model the response of prices is pinned down by three parameters the precision of available information about the nominal shock the frequency of price adjustment and the degree of strategic complementarity in pricing decisions this result synthesizes the broader lessons of the pertinent literature however this synthesis provides only a partial view of the role of incomplete information once one allows for more general information structures than those used in previous work one cannot quantify the degree of price inertia without data on the dynamics of higher order beliefs or of the agents forecasts of inflation we highlight this with three extensions of our baseline model all of which break the tight connection between the precision of information and higher order beliefs featured in previous work

public information private information and the multiplicity of equilibria in coordination games abstract i study coordination games with incomplete public and private information and relate equilibrium convergence to convergence of higher order beliefs as the players signals become more and more precise the equilibrium manifold converges to the correspondence of common knowledge equilibria whenever the variance of the public signal converges to 0 at a rate faster than one half the rate of convergence of the variance of private signals the same condition also determines the convergence of common p belief to common knowledge which leads to a simple intuition for its origin and an immediate generalization of the former results about equilibrium convergence journal of economic literature classification numbers c72 d82

rational behavior with payoff uncertainty abstract the iterated deletion of weakly dominated strategies has been advanced as a necessary requirement for rational play however this requirement relies on the assumption that the players have no doubts about their opponents payoffs we show that once such doubts are introduced all that can be justified by an appeal to rationality is one round of deletion of weakly dominated strategies followed by iterated deletion of strategies that are strongly dominated this extends the fudenberg kreps and levine j econ theory 12 1988 354 380 study of the robustness of nash equilibrium refinements to the robustness of solution concepts based only on rationality our results also clarify the relationship between various notions of what it means for payoff uncertainty to be small

monetized value of the environmental health and resource externalities of soy biodiesel abstract this study monetizes the life cycle environmental damage human health risk and resource depletion externalities associated with the production and use of biodiesel fuels from soybean feedstock applying a framework that couples life cycle damage measurements with social preferences elicited from a conjoint choice experiment allows for comparison of petrodiesel and biodiesel s external damages the results of the study reveal that production and consumption of soybean based biodiesels produce improvements in environmental health and resource impacts of 0 27 per gallon relative to petrodiesel for a 20 blend and 3 14 per gallon for a 100 blend

an axiomatic theory of a risk dominance measure for bipolar games with linear incentives bipolar games are normal form games with two pure strategies for each player and with two strict equilibrium points without common equilibrium strategies a normal form game has linear incentives if for each player the difference between the payoffs for any two pure strategies depends linearly on the probabilities in the mixed strategies used by the other players a measure of risk dominance between two strict equilibrium points of a bipolar game with linear incentives is characterized by 11 axioms journal of economic literature classification number c72

banking competition and market efficiency this paper analyses competition among financial intermediaries in a set up where financial intermediaries economize on duplicated monitoring diamond 1984 we analyse two different games in which both direct trade and indirect trade are available we show that in general equilibrium outcomes are inefficient so that diamond s efficiency result is fragile intermediation may increase rather than decrease transaction costs disintermediation may also be an equilibrium we discuss the role played by the nonconvexities of banks technology and that played by competition for deposits and loans

solar subsidies and economic efficiency abstract in this paper the case for subsidies for solar energy to counter inefficient pricing practices of electric utilities hidden subsidies to non solar fuels and tax law biases are examined the conclusion reached for two of three regions in the usa in the case of solar energy replacing electricity for hot water heating is that far from offsetting biases against solar energy current subsidies reinforce pre existing biases in favour of the use of solar energy systems

contagion and uninvadability in local interaction games the bilingual game and general supermodular games abstract in a setting where an infinite population of players interact locally and repeatedly we study the impacts of payoff structures and network structures on contagion of a convention beyond 2 2 coordination games first we consider the bilingual game where each player chooses one of two conventions or adopts both i e chooses the bilingual option at an additional cost for this game we completely characterize when a convention spreads contagiously from a finite subset of players to the entire population in some network and conversely when a convention is never invaded by the other convention in any network we show that the pareto dominant risk dominant resp convention is contagious if the cost of bilingual option is low high resp furthermore if the cost is in a medium range both conventions are each contagious in respective networks and in particular the pareto dominant convention is contagious only in some non linear networks second we consider general supermodular games and compare networks in terms of their power of inducing contagion we show that if there is a weight preserving node identification from one network to another then the latter is more contagion inducing than the former in all supermodular games

price wars and the stability of collusion a study of the pre world war i bromine industry between 1885 and 1914 us bromine producers colluded to raise prices and pro ts this collusion was disrupted by price wars bromine price wars are compared with the green porter and abreu pearce stacchetti models some price wars resulted from the imperfect monitoring problems which motivate these models several empirical implications of the aps model are borne out but the bromine industry s price wars were generally milder than contemplated by aps more severe price wars were part of a bargaining process in which rms tried to force renegotiation to a new collusive equilibrium with a diierent distribution of rents

rational expectations business cycles in search equilibrium we examine the rational expectations equilibrium paths of the model of search and barter in diamond s aggregate demand management in search equilibrium for some initial positions there are two equilibrium paths converging to different steady states with the high activity path pareto dominating the low activity path with some parameters there is also a continuum of equilibrium paths converging to another steady state moreover there can be cycles that are equilibrium paths even though the environment is stationary

intertemporal coordination with delay options abstract this paper studies equilibrium selection in intertemporal coordination problems with delay options the risk dominant action of the underlying one shot game is selected when frictions are arbitrarily small larger frictions introduce real option effects in the model and inhibit coordination

government policy and the probability of coordination failures this paper introduces an approach to the study of optimal government policy in economies characterized by a coordination problem and multiple equilibria such models are often criticized as not being useful for policy analysis because they fail to assign a unique prediction to each possible policy choice we employ a selection mechanism that assigns ex ante a probability to each equilibrium indicating how likely it is to obtain we show how such a mechanism can be derived as the natural result of an adaptive learning process this approach leads to a well defined optimal policy problem and has important implications for the conduct of government policy we illustrate these implications using a simple model of technology adoption under network externalities

characterising equilibrium selection in global games with strategic complementarities abstract global games are widely used to predict behaviour in games with strategic complementarities and multiple equilibria we establish two results on the global game selection first we show that for any supermodular complete information game the global game selection is independent of the payoff functions chosen for the game s global game embedding second we give a simple sufficient criterion to derive the selection and establish noise independence in many action games by decomposing them into games with smaller action sets to which we may often apply simple criteria we also report in which small games noise independence may be established by counting the number of players or actions

risk dominance and perfect foresight dynamics in n player games abstract in perfect foresight dynamics an action is linearly stable if expectation that people will always choose the action is self fulfilling a symmetric game is a pim game if an opponent s particular action maximizes the incentive of an action independently of the rest of the players this class includes supermodular games games with linear incentives and so forth we show that in pim games linear stability is equivalent to u dominance a generalization of risk dominance and that there is no path escaping a u dominant equilibrium existing results on n player coordination games games with linear incentives and two player games are obtained as corollaries

communication and coordination in social networks i model people in a coordination game who use a communication network to tell each other their willingness to participate the minimal sufficient networks for coordination can be interpreted as placing people into a hierarchy of social roles or stages initial adopters then followers and so on down to late adopters a communication network helps coordination in exactly two ways by informing each stage about earlier stages and by creating common knowledge within each stage we then consider two examples first we show that low dimensional networks can be better for coordination even though they have far fewer links than high dimensional networks second we show that wide dispersion of insurgents people predisposed toward participation can be good for coordination but too much dispersion can be bad although collective action depends on both social structure and individual incentives these integral aspects have been formalized separately in the fields of social network theory and game theory by considering them together this paper engages the classic question of which structures are conducive to coordination and shows that structure and strategy are related in a mutually interesting way here we consider a coordination game in which each person wants to participate only if others participate social structure is thought of as a communication network by which people tell each other their willingness to participate each person knows whether her neighbours in the network are willing but does not know about anyone else our model is thus a game of incomplete information in which each person given his local knowledge decides whether to participate the main result is a characterization of the minimal sufficient networks for coordination in terms of a hierarchy of social roles or stages initial adopters then followers and so on down to late adopters for example a communication network helps coordination in exactly two ways by informing each stage about earlier stages and by creating common knowledge within each stage we also consider two simple examples first we show that low dimension or strong link networks can be better for coordination even though they have far fewer links than high dimension or weak link networks second we show that wide dispersion of insurgents people predisposed toward participation can be good for coordination but too much dispersion can be bad this paper is built on the assumption that the most basic and common mechanism for coordination is the i ll go if you go mechanism individuals first communicate with each other about their preferences and then each individual chooses whether to participate or not hence a person s participation depends on what he knows about his neighbours it does not depend solely on their participation itself either through learning adaptation or social influence the physical analogies of contagion or diffusion are not

p dominance and perfect foresight dynamics abstract we investigate stability of p dominant equilibria under perfect foresight dynamics we show that a strict p dominant equilibrium with i p i 1 is globally accessible and absorbing in perfect foresight dynamics we also investigate robustness and extensions of this result we apply our proof method to games with u dominant equilibria and unanimity games

noise independent selection in multidimensional global games abstract this paper examines many player many action global games with multidimensional state parameters it establishes that the notion of noise independent selection introduced by frankel morris and pauzner d frankel s morris a pauzner equilibrium selection in global games with strategic complementarities j econ theory 108 2003 1 44 for one dimensional global games is robust when the setting is extended to the one proposed by carlsson and van damme h carlsson e van damme global games and equilibrium selection econometrica 61 1993 989 1018 more precisely our main result states that if an action profile of some complete information game is noise independently selected in one dimensional global games then it is also noise independently selected in all multidimensional global games

optimal departures from marginal cost pricing focuses on departures from marginal cost pricing optimal allocation or resources level of tax revenue that will be collected by the government theorems developed for resource allocation ebsco

rationalizable foresight dynamics abstract this paper proposes and studies the rationalizable foresight dynamics a normal form game is repeatedly played in a random matching fashion by a continuum of agents who make decisions at stochastic points in time a rationalizable foresight path is a feasible path of action distribution along which each agent takes an action that maximizes his expected discounted payoff against another path which is in turn a rationalizable foresight path we consider a set valued stability concept under this dynamics and compare it with the corresponding concept under the perfect foresight dynamics

sincere voting in large elections abstract austen smith and banks 1996 showed that sincere informative voting is not typically an equilibrium of the condorcet voting model when the size of the electorate is large here we reverse their finding by adding a third type of voter one that receives no information in favor of either of the alternatives as well as global uncertainty about the probability that each voter is such a no evidence type the expected number of no evidence type voters can be arbitrarily small nevertheless if the electorate is large enough then each of the two standard condorcet types votes sincerely in every nondegenerate type symmetric equilibrium

an approach to equilibrium selection abstract we consider equilibrium selection in 2 2 bimatrix both symmetric and asymetric games with two strict nash equilibria by embedding the static games in a dynamic random matching framework played by a continuum of anonymous agents unlike in evolutionary games the players are rational and maximize discounted payoffs but they are restricted to make a short run commitment when choosing actions this dynamic game with frictions has stationary states which correspond to the nash equilibria of the static game our selection is based on differential stability properties of the stationary states it is shown that for a small degree of friction a strict nash equilibrium becomes uniquely absorbing and globally accessible if and only if it is risk dominant harsanyi and selten a general theory of equilibrium selection in games mit press cambridge ma 1988 journal of economic literature classification numbers c72 and c73