minimax regret and strategic uncertainty this paper introduces a new solution concept a minimax regret equilibrium which allows for the possibility that players are uncertain about the rationality and conjectures of their opponents we provide several applications of our concept in particular we consider pricesetting environments and show that optimal pricing policy follows a non degenerate distribution the induced price dispersion is consistent with experimental and empirical observations baye and morgan 2004

impossibility of speculation theorems with noisy information the impossibility of speculations result implied by some models of information economics seems to follow directly from the strong assumptions concerning the information structure in the relevant models this paper investigates whether the impossibility result hold when some noise is introduced into the information system in a no trade model it is proved that when the degree of noise approaches zero the noisy model converges to the impossibility result of the no noise model yet it is shown that the introduction of some positive noise into the information system can disrupt the impossibility result in many applications journal of economic literature classification numbers 024 026

trade with heterogeneous prior beliefs and asymmetric information no trade theorems have shown that new information will not lead to trade when agents share the same prior beliefs this paper explores the structure of no trade theorems with heterogeneous prior beliefs it is shown how different notions of efficiency under asymmetric information ex ante interim ex post are related to agents prior beliefs as well as incentive compatible and public versions of those efficiency concepts these efficiency results are used to characterize necessary and sufficient conditions on agents beliefs for no trade theorems in different trading environments

an equity assessment of introducing uncertain forest carbon sequestration in eu climate policy large emissions of greenhouse gases are expected to cause major environmental problems in the future european policy makers have therefore declared that they aim to implement cost efficient and fair policies to reduce carbon emissions the purpose of this paper is to assess whether the cost of the eu policies for 2020 can be reduced through the inclusion of carbon sequestration as an abatement option while equity is also improved the assessment is done by numerical calculations using a chance constrained partial equilibrium model of the eu emissions trading scheme and national effort sharing targets where forest sequestration is introduced as an uncertain abatement option fairness is evaluated by calculation of gini coefficients for six equity criteria to policy outcomes the estimated gini coefficients range between 0 11 and 0 32 for the current policy between 0 16 and 0 66 if sequestration is included and treated as certain and between 0 19 and 0 38 when uncertainty about sequestration is taken into account and policy makers wish to meet targets with at least 90 per cent probability the results show that fairness is reduced when sequestration is included and that the impact is larger when sequestration is treated as certain

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

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

equity development and climate change control the paper analyzes the effects of different equity principles on the decision of developing countries to join a world coalition whose aim is to control greenhouse gas emissions a game theoretic framework is proposed to assess the incentives for different countries to sign an international treaty on climate change control then the effects of different equity rules on these incentives are evaluated by using a dynamic integrated growth and climate model policy proposals based on transfers from developed to developing countries are also analyzed jel c7 h0 h3 q38

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

international equity and differentiation in global warming policy ne of the major obstacles to reaching a comprehensive agreement on global warming is the setting of greenhouse gas emission reduction targets for individual countries long standing tensions between industrialized and developing countries have raised the issue of equity in burden sharing moreover individual industrialized nations have pleaded special circumstances and have sought differentiation in their obligations this paper analyzes alternative rules for distributing tradable carbon dioxide emissions permits a non linear programming model which distinguishes between allocation based and outcome based rules is used to analyze the relative welfare outcomes the model is applied to the world body of nations and yields several important policy implications

differential interpretation of information in inflation forecasts we test the hypothesis associated with a standard assumption in the theoretical literature on learning that economic agents interpret information identically we use a data set based on a survey o

the political economy of trade liberalization in the transition abstract baldwin and baldwin 1996 review explanations for trade liberalization in developed market economies in particular exchange of market access appears important hillman and moser 1996 for economies in transition technological inferiority and contemporaneous privatization distinctly form part of the scenario for trade liberalization and are basic ingredients in a model describing liberalization policies we begin here with background observations and proceed to a model which ties together politically constrained trade liberalization opportunities and privatization of technologically disadvantaged enterprises the model draws on a more extensive presentation in hillman et al 1996

alternate approaches to the political economy of endogenous trade liberalization abstract trade liberalization is puzzling from the perspective of standard political economy models why would a government find it optimal to remove protection that it previously found optimal to impose this paper reviews two types of approaches to answering this question approaches that view liberalization driven by strenghtened anti protection forces and approaches that view liberalization driven by an erosion of pro protection forces

no trade and yes trade theorems for heterogeneous priors abstract we show that contrary to currently widely held misperceptions the classical no trade theorem obtains even under heterogeneous priors that is when priors are not common speculative trade is still impossible under common knowledge of rationality however trade becomes mutually acceptable if at least one party to the trade puts at least some slight probability on the other party being irrational we also derive bounds on disagreements in the case of heterogeneous priors and common p beliefs

equity in climate change an analytical review how global emissions reduction targets can be achieved equitably is a key issue in climate change discussions this paper presents an analytical framework to encompass contributions to the literature on equity in climate change and highlights the consequences in terms of future emissions allocations of different approaches to equity progressive cuts relative to historic levels for example 80 percent by industrial countries and 20 percent by developing countries in effect accord primacy to adjustment costs and favor large current emitters such as the united states canada australia oil exporters and china in contrast principles of equal per capita emissions historic responsibility and ability to pay favor some large and poor developing countries such as india indonesia and the philippines but hurt industrial countries as well as many other developing countries the principle of preserving future development opportunities has the appeal that it does not constrain developing countries in the future by a problem that they did not largely cause in the past but it shifts the burden of meeting climate change goals entirely to industrial countries given the strong conflicts of interest in defining equity in emission allocations it may be desirable to shift the emphasis of international cooperation toward generating a low carbon technology revolution equity considerations would then play a role not in allocating a shrinking emissions pie but in informing the relative contributions of countries to generating such a pie enlarging revolution

the fundamentals of the future international emissions trading system the study aims to analyze the sectoral marginal abatements cost curves for a number of eu countries as well as to examine the efficiency aspects and the economic impacts for the major sectors of the ets under different carbon market configurations in 2010 and 2020 to produce a consistent and realistic assessment we employ sources such as ghg national inventories naps and poles world energy model to constitute the sectoral base year and 2010 2020 emission levels in different countries and regions we then use the market analysis tool aspen which enables to derive supply and demand from sectoral maccs produced with the poles model and to evaluate the economic impacts on the carbon market participants the paper shows that in compliance with the kyoto targets the benefits of an enlarged carbon market are significant since more than 50 of the abatement in the short term have to be achieved in ets sectors which may indeed use cdm or ji credits a second major conclusion is that in 2020 the new flexibility margins provided by the adjustment of investments in new capacities compensate for the increase in pressure towards stronger emission reductions this reduces the relative importance of the enlarged carbon market

analysis of the eu policy package on climate change and renewables abstract in 2009 the eu decided to reduce greenhouse gas emissions at least by 20 in 2020 compared to 1990 and to supply 20 of energy needs by 2020 from renewable energy sources this paper uses an energy model coupled with a non co 2 greenhouse gas model to assess the range of policy options that were debated to meet both targets policy options include trading of renewable targets carbon trading in power plants and industry and the use of the clean development mechanism to improve cost efficiency the models also examined fairness by analysing the distribution of emission reduction in the non emission trading sector the distribution of co 2 allowances in the emission trading sector and the reallocation of renewable targets across member states the overall costs of meeting both targets range from 0 4 to 0 6 of gdp in 2020 for the eu as a whole the redistribution mechanisms employed significantly improve fairness compared to a cost effective solution

common beliefs and the existence of speculative trade abstract this paper shows that if rationality is not common knowledge the no trade theorem of milgrom and stokey fails to hold we adopt monderer and samet s notion of common p belief and show that when traders entertain doubts about the rationality of other traders arbitrarily large volumes of trade as well as rationality may be common p belief for a large p furthermore rationality and trade may simultaneously be known to arbitrary large but finite degree journal of economic theory classification numbers c70 d82 d84

stochastic carbon sinks for combating carbon dioxide emissions in the eu abstract this paper carries out numerical calculations on the potential of carbon sinks in the eu emissions trading scheme ets and national commitments under conditions of stochastic carbon dioxide emissions from fossil fuels and carbon sequestration by forests chance constraint programming is used to analyze the role of stochastic carbon sinks for national and eu wide compliance costs the analytical results show that the inclusion of the carbon sink option can reduce costs for low enough marginal cost and risk discount but also that costless carbon sinks as by products from forestry are not part of a cost effective solution under a high reliability concern cost savings are reduced due to risk discounting under a reliability concern in particular when assigning chebyshev s inequality as compared with a normal probability distribution it is also shown that the supply of forest sinks on the market depends on the differences in marginal abatement cost between the trading and the non trading sectors and in risk discounting between achievements of the ets cap and the national commitment relatively low marginal abatement cost in the non trading sector and high risk discounting of national commitment achievements increase the supply of sinks in the market and hence reduces the equilibrium price the empirical application illustrates the importance of risk discounting for the magnitude of cost savings obtained from introducing forest carbon sinks in the eu ets and national commitments

coherence causality and effectiveness of the eu environmental policy system results of complementary statistical and econometric analyses this paper presents the first empirical test of coherence i e consistency of policies within a framework causality i e logical priority of objectives over policies and effectiveness i e ability of policies to tackle challenges as defined by objectives of the overall eu environmental policy system to do so i applied complementary statistical cross sectional and time series and econometric dynamic tri probit analyses to an original panel dataset based on addressed issues i e pollution vs resource trans boundary vs domestic flow vs stock rather than on implemented policies i e eu legislation aiming at optimal pollution production optimal resource use and market competition it would be impossible to perform similar analyses by referring to realized policies rather than tackled issues due to the unbalanced sample characterizing the former with respect to the latter as well as due to overlapping objectives interrelated policies and non univocal relationships between objectives and policies in contrast with previous studies of single eu environmental policies characteristics of the eu environmental policy or eu environmental objectives i found that the overall eu environmental policy system is internally coherent dynamically causal and ex ante effective moreover the evidence suggests that many issues are correlated trans boundary issues became more relevant in 2012 pollution production was more significant than resource use and flow issues were more important than stock issues from 1995 to 2010 finally i show that few objectives overlapped a safe environment objective 1987 1997 was preferred to a greenhouse gas ghg reduction objective 2003 2012 but pursued with a 2 year lag although the latter has recently become preferred to the former in addition a ghg reduction objective was preferred to a sustainable development objective 1998 2002