history dependence in concave economies abstract this paper investigates concave intertemporal optimization problems and derives two mechanisms either growth or control state interactions e g due to endogenous preferences that allow for multiple steady states including an unstable one therefore history dependence is possible in a perfectly governed economy subject to the law of diminishing returns if one of these two mechanisms is present this result complements a large amount of literature that attributes history dependence to convexities as a consequence lock ins into undesired evolutions are possible beyond the familiar case of increasing returns

nonconvexities in optimal pollution accumulation abstract with a few exceptions the analysis of optimal pollution accumulation or detrimental stock externalities rests on the assumptions that the level of damage is unbounded and that pollution decay increases monotonically with the level of pollution stock we show that these assumptions are restrictive and that their generalization alters the basic economic properties of optimal pollution control we specify a decay function which is concave with low stock levels and convex when pollution is higher we show that although multiple steady states may exist the globally optimal solution may be independent of the initial pollution level it is also possible that there are cutoff levels which determine the optimal long run equilibrium implying that the feedback control law is discontinuous and nonmonotonic bounded damage may have similar implications but in contrast to concave convex decay they may occur even with zero discounting

putting the present value model into practice a comparison of two alternative approaches abstracta key issue around putting the present value model into practice is how to construct the unobserved future expectations of the fundamental variables related to an asset one approach is to fit a vector autoregression var for the fundamental variables and deduce their future expectations from the estimated var an alternative is to directly specify the future expectations as unobserved components uc and use the kalman filter to extract their estimates from the realized data this article examines whether the predictions of the present value model are consistent across the two approaches constructing the var and uc versions of the standard present value model we examine how the two versions compare in identifying the main driver of the us and uk housing markets for the uk the two approaches consistently attribute most variations in the price rent ratio to the expected future risk premium for housing investment for the us however the two approaches deliver considerably different results t

the concept of natural capital the natural environment is now commonly viewed as a form of capital asset or natural capital also included are ecosystems that provide important goods and services to the economy managing natural capital has consequences for sustainable development however there are contrasting weak versus strong sustainability views which in turn have implications for green accounting natural resource based sovereign wealth funds have emerged as key financial instruments for compensating resource depreciation with greater economy wide investments recent scientific evidence recommends demarcating safe operating spaces to limit exploitation of critical global biophysical subsystems or processes these challenges suggest that the concept of natural capital is pivotal to sound policy

production and conflict models versus rent seeking models a production and conflict p c model and a rent seeking rs model are compared for one group two groups and k groups adding a new agent enlarges the pie in the p c model but causes the fixed size pie to be allocated on one more rent seeker in the rs model the total production or rent is distributed within and between groups according to the within group and between group decisiveness productive and fighting efficiencies and group sizes play a role the collective action problem is more severe for the rs model as group size increases the ratio of within group to between group fighting increases marginally toward a constant for the p c model while it increases convexly for the rs model adding an additional agent to each of two groups is more detrimental to the utilities in rs groups than in p c groups while adding a second group of agents when there is already one group of agents gives the reverse result the severe between group fighting in the p c model for many groups causes the p c model to be preferable for few groups while the rs model is preferable for many groups applications are considered to intergroup migration inside versus outside ownership divestitures mergers and acquisitions multidivisional versus single tier firms and u form versus m form of economic organization

microfoundations of macroeconomic fluctuations and the laws of probability theory the principle of large numbers versus rational expectations arbitrage abstract the principle of large numbers shows that the relative deviation for a macro system with n independent elements is of the order of 1 n lucas approach to a microfoundations for macroeconomic fluctuations is thus not capable of explaining the magnitude of observed macroeconomic fluctuations arbitrage activity would largely eliminate correlations created by rational expectations among economic agents when they face counter movements in relative prices the complex nature of many body problems and the statistical feature of aggregate indexes cannot be ignored in a micro macro modeling intermediate structures such as financial markets and industrial organizations are more important than households and firms in generating business cycles

optimal and open access harvesting of multi use species in a second best world expansion of human populations and activities has caused increased conflicts between wildlife and humans as a result the distinction between resource and pest species has become blurry we propose an economically based classification of species based on a multi use bioeconomic model the classification of the steady state population of a species is shown to depend on both species density and economic factors we extend earlier work on multi use resource pest species by applying the theoretical model to a developing country context where property rights to wildlife are imperfectly enforced so that second best trade measures are often applied by the international community to promote conservation upon calibrating the model using data for the african elephant we derive three further results first when comparing the optimal stock of a multi use species to the open access stock we find that the ranking in terms of abundance is ambiguous second and consistent with existing literature on resource management in a second best world our case study supports the idea that trade bans have ambiguous effectson wildlife abundance third due to a bifurcation effect characterizing the multi use model s solution strategic and temporary subsidizing by the north may enable them to free ride on conservation efforts of the south henceforth

economic activity in the shadow of conflict i introduction production prices and welfare are altered when exchange emerges in an autarkic economy these same variables are likewise affected when appropriation arises in a production and exchange economy consider robinson crusoe who allocates resources to clothing and food the implicit relative price of clothing and the production consumption point are determined by crusoe s preferences and production possibilities when friday appears and exchange enters crusoe s world there is a change in all of the fundamental economic variables relative price production consumption and utility but suppose friday has the capacity to profitably seize some or all of crusoe s goods or resources crusoe might guard against such a contingency by building defenses sufficient defenses could induce friday to carry out an exchange that might otherwise not occur by allocating some of his resources to defense crusoe alters economic fundamentals including the existence of exchange itself throughout its history economics has generally ignored the effects of appropriation possibilities on production and exchange often however the three economic activities are enmeshed according to barraclough 1994 specialized production and trade became quite extensive in the ancient eurasian world because empires could provide protection for trading links more recently european colonial powers created trading empires based upon strong navies skaperdas and syropoulos 1996 mansfield 1994 today within russia and china there are numerous examples of intertwined production exchange and appropriation even in commonplace crime these activities can be interdependent a potential shoplifter could steal if the store s defenses are low or trade if defenses are high 1 when appropriation possibilities are overlooked the results of standard trade models can be misleading when the role of exchange is ignored the predictions of conflict models can be erroneous economists need a new class of models designed to investigate economic activity in the shadow of conflict where production exchange and appropriation are intertwined pure trade and pure conflict models will be special cases of these new integrated models 2 the fundamental goal of this paper is to contribute to the theoretical development of the new class of integrated models of production exchange and appropriation specifically we model a one time interaction between two agents as a sequential predator prey game with the potential for ricardian trade think of crusoe as a potential prey and friday as a potential predator crusoe moves first by allocating some resources to defensive fortifications to protect his remaining resources friday moves second and faces two options either allocate some resources to weapons in hope of seizing resources from crusoe or produce no weapons and pursue specialized production and trade the economic interactions among appropriation production and exchange depend on key parameters in the model relative resource endowments effectiveness of offensive weapons against defensive fortifications and weapons and consumer goods productivities within the model we show how conflict can be subdued by the potential of mutually beneficial exchange but at a resource cost that modifies fundamental economic variables like relative price production trade volume gains from trade and security of property the model also identifies the conditions under which conflict is so powerful that specialized production and trade cannot emerge further we discover that the integrated model opens up a new way to think about and measure the gains from trade a predator may gain from trade relative to predation or autarky but prefer that the exchange institution be precluded alternatively a predator may be indifferent about trade relative to predation or autarky but gain from the trade institution in section ii we present a general theoretical framework for integrating production exchange and appropriation in a one shot sequential game

the control of invasive species on private property with neighbor to neighbor spillovers invasive pests cross property boundaries property managers may have private incentives to control invasive species despite not having sufficient incentive to fully internalize the external costs of their role in spreading the invasion each property manager has a right to future use of his own property but his property may abut others properties enabling spread of an invasive species the incentives for a foresighted property manager to control invasive species have received little attention we consider the efforts of a foresighted property manager who has rights to future use of a property and has the ability to engage in repeated discrete control activities we find that higher rates of dispersal associated with proximity to neighboring properties reduce the private incentives for control controlling species at one location provides incentives to control at a neighboring location control at neighboring locations are strategic complements and coupled with spatial heterogeneity lead to a weaker link public good problem in which each property owner is unable to fully appropriate the benefits of his own control activity future use rights and private costs suggest that there is scope for a series of coase like exchanges to internalize much of the costs associated with species invasion pigouvian taxes on invasive species potentially have qualitatively perverse behavioral effects a tax with a strong income effect e g failure of effective revenue recycling can reduce the value of property assets and diminish the incentive to manage insects on one s own property

some evidence in favor of a monetary rational expectations exchange rate model with imperfect capital substitutability the authors develop and test a monetary rational expectations model of the swiss u s exchange rate two salient features of the model are the assumption that domestic and foreign currency denominated assets are imperfect substitues and that purchasing power parity need not hold the authors fail to reject overidentifying restrictions imposed on the model by the rational expectations hypothesis their point estimates especially for the income elasticity of the demand for money are plausible finally the model outperforms the random walk model established as a benchmark by r a meese and k s rogoff 1983 copyright 1992 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association

conflict the sire of exchange violence is the sire of all the world s values robinson jeffers abstract utilizing a model of conflict with two goods three activities production predation and defense the paper shows that uncontested exchange is an impossibility all exchange is contested through a bargaining game extension of a predation game a characterization of an exchange spectrum is developed the metric for these exchange possibilities is based on threats of predation and exploitation i e conflict uncontested exchange walrasian market exchange is but one point along this spectrum and is not robust to exploitation

thresholds in concave renewable resource models abstract a number of renewable resource models some of them just recently published e g about shallow lakes refer to convexities with respect to the resource stock as the source for multiple steady states and associated thresholds this short paper draws attention to the fact that multiple steady states and thresholds are possible in well behaved i e concave models too the ecological consequence is that renewable resource management is sensitive to initial conditions in more cases than so far suggested in the literature

a general equilibrium model of two group conflict with endogenous intra group sharing rules this paper explores the interactions among intra group sharing rules the competition between two groups over the common pool of output and the allocation of resources between productive and appropriate activities in the interior solution the use of egalitarian method for the distribution of group income among members plays no distributional role but only affects the allocation of resources it releases resources into the productive sector from the group that adopts the egalitarian rule by making the internal conflict among the members less intense the sequential choice of intra group sharing rules and resource allocations produce the adoption of fully egalitarian intra group sharing rules in both groups these rules minimize the amount of resources allocated to appropriate activities and maximize the welfare level of all individuals in the economy this result suggests that inter group competition with the use of egalitarian principle in the distribution of group income among group members which is not available to the hobbesian state of nature is one of the cheaper social devices in restraining individuals from engaging in costly appropriative activities

the distribution of income in the presence of appropriative activities we examine the distribution of income when agents allocate their initial endowments between production and appropriation arms investments influence or rent seeking activities final output depends on the productive contributions of the agents but is divided between them according to their relative contributions in appropriation various possible improvements in an agent s useful productivity reduce the agent s equilibrium share of income but increases in initial endowments increase an agent s share we contrast our results to those that would obtain in the competitive counterpart to our model and discuss its relevance both for history and for the present the results extend to a class of models where distribution is determined between two groups of agents with agents within each group behaving non cooperatively but without exhibiting the free rider problem

whether to attack a terrorist s resource stock today or tomorrow reprinted from games and economic behavior 64 2 kjell hausken whether to attack a terrorist s resource stock today or tomorrow pages no 548 564 copyright 2008 with permission from elsevier

anarchy and its breakdown anarchy defined as a system in which participants can seize and defend resources without regulation from above is not chaos but rather a spontaneous order however anarchy is fragile and may dissolve either into formless amorphy or into a more organized system such as hierarchy under anarchy each contestant balances between productive exploitation of the current resource base and fighting to acquire or defend resources anarchy is sustainable only when there are strongly diminishing returns to fighting effort the decisiveness parameter is sufficiently low and incomes exceed the viability minimum these considerations explain many features of animal and human conflict

deterrence preemption and panic a common enemy problem of terrorism we develop a game theoretic analysis of terrorism that examines the interaction between a terrorist organization and multiple target countries and considers both pre emption and deterrence as counter terrorist policies the damage from terror includes not only the material cost of fatality injury and loss of property but also the resultant fear the fear effect leads to different kinds of equilibria and implications for counter terrorism policies in particular the model identifies conditions under which greater pre emption may be the rational response to an increase in terrorism i e it analyzes the merit of the dictum offense is the best defense further it examines the characteristics of cooperative behavior among target countries in dealing with the threat of terrorism

capital investment for optimal exploitation of renewable resource stocks in the age of global change abstract the world is rapidly changing and biotic resources and their users are adapting determining how ecological and economic interactions determine the outcomes of this adaptation is critical to understanding the future of natural resources we model a two species fisheries as a stylized system to investigate the adaptation strategies of a harvester faced with shifting species composition in an ecological community we explore how interspecies interactions and pricing effects jointly determine the optimal adaptation strategy we consider two interacting species that are harvested jointly but where the harvester may exert effort towards each species differentially provided she invests in reproducible capital that allows targeting the possible adaptation strategies comprise changes in how people interact with natural capital for example changing harvest levels and investment in reproducible or human capital which may be a substitute or complement for natural capital stocks we find that the market price of the harvested species exerts a particularly strong impact on the adaptation strategy all else equal unequal prices tends to drive extreme targeting or avoidance of a new species economic and ecological factors can necessitate investment at equilibrium and early transient management decisions for beneficial species may like with nuisance species produce large benefits

a strategic analysis of the war against transnational terrorism abstract we study a two stage game in which a transnational terrorist organization interacts with an arbitrary number of countries that may differ in their political or economic power their military effectiveness the benefit from cooperating against terrorism and the value they assign to damage only a subset of countries that emerges endogenously takes proactive measures to fight the terrorist while all countries incur defensive expenditures to protect their soil we characterize analytically the pure strategy subgame perfect equilibrium of the game and show how the equilibrium strategies depend on the key model parameters we provide an algorithm to find the endogenous set of cooperating countries based on their benefit from cooperation and their political economic power

biology as a source of non convexities in ecological production functions generating ecological production functions including harvest yield functions is a high priority research area most yield functions used in economics and ecology rely on convexity properties of species growth functions but convexity is shown here to depend on whether realistic biology is incorporated optimizing behavior by individual organisms is connected with species population dynamics in order to derive growth functions in a general equilibrium ecosystem model non convexities are shown to be an inherent property of the growth functions owing to familiar biological processes including predator prey and competitive relations predator satiation and prey substitution the growth functions generate yield functions that are problematic for management because they exhibit kinked average revenue curves discontinuous marginal revenue curves and knife edge optimum effort levels where a small increase above the optimum effort can rapidly deplete the stock these phenomena can be explained entirely by the underlying biological processes

ecosystems externalities and economies this paper incorporates an ecosystem model into a model of a simple economy the decisionmaking agents in the ecosystem are individual organisms aggregated to the species level a species may provide utility directly to humans or it may provide utility indirectly because it is used either as a raw material in goods fabrication or as sustenance for other species we describe a comparative static equilibrium of the ecosystem where species demands for other species are equal to the supplies of those other species and energy is conserved the ecosystem is then embedded in the economy so that the effects of human intervention can be traced through both the ecosystem and the economy human intervention creates ecosystem externalities such that ecosystem equilibria are shifted and the new equilibria affect the utility or the production processes of other humans this framework allows us to describe in principle which ecosystem services can be efficiently usurped by humans which waste flows can be efficiently allowed into ecosystems and which ecosystem organisms and physical attributes can be efficiently maintained

optimal ecosystem management when species compete for limiting resources abstract resource based models of species competition have been introduced recently as an alternative to the classical theory based on the lotca volterra methodological approach to species competition we consider economic management of an ecosystem for a tilman model of mechanistic resource based species competition where the growth of species is limited by resource availability we analyze the equilibrium ecosystem state resulting from nature s equilibrium and two basic management problems the privately optimal management problem and the socially optimal management problem under private optimization agents do not take into account externalities associated with the effects of their management practices on ecosystem service flows while these effects are accounted for at the socially optimal management we show that in general three different equilibrium species specialization patterns emerge we completely characterize these patterns for the ecological economic model with linear structure and we provide policy rules so that the privately optimal state could be driven toward the socially optimal or the natural equilibrium we also develop an approach for unifying equilibrium price theory with tilman ecological modeling and we prove the existence and analyze the stability of a price equilibrium for a stochastic discrete choice model of species specialization finally we discuss equilibrium specialization and policy issues for a generalized model where species and resources interact among themselves as a conceptual basis for incorporating detailed ecological modeling into economic management

the economics of non convex ecosystems introduction the word convexity is ubiquitous in economics but absent from economics in this paper we explain why and show what difference it makes to economic analysis if ecosystem non convexities are taken seriously a simple proof is provided of the connection between self similarity and power laws we also provide an introduction to each of the papers in the symposium and draw out the way in which they form a linked set of contributions

revenge or continued attack and defense in defender attacker conflicts abstract existing literature has demonstrated that exacting revenge can have a self deterrence effect and a value of revenge effect the former means that each player will decrease effort when competing for a resource because of fear of a rival s revenge while the latter implies that each player will increase effort in the revenge period moreover the self deterrence effect could outweigh the value of revenge effect implying that revenge could be helpful in stabilizing conflicts a phenomenon known as the paradox of revenge we re examine the two effects and the paradox of revenge in defender attacker conflicts considering a scenario in which a defender and only the defender who was attacked in the first period takes revenge on the attacker in the subsequent period we demonstrate that whether or not these results hold depends on how much the defender values revenge and the difference between the two players efficiencies of effort more interestingly we show that a sufficiently large revenge value for the defender can deter an attack from the attacker in the first place

multi battle contests an experimental study this study examines behavior of subjects in simultaneous and sequential multi battle contests in simultaneous contests subjects make positive bids in each battle 80 of the time and bids fall within the predicted boundaries however 35 of the time subjects make positive bids in only two instead of all three battles and they significantly overuse moderately high bids in sequential contests theory predicts sizable bids in the first battle and no bids in the subsequent battles contrary to this prediction subjects significantly underbid in the first battle and overbid in subsequent battles consequently instead of always ending in the second battle contest proceeds to the third battle 38 of the time finally in both simultaneous and sequential settings subjects make higher aggregate bids than predicted resulting in negative expected payoffs

non convexities in continuous time investment theory that non convex preferences or technologies cause problems for economic theory is well known in recent years there have been numerous contributions to the nonconvexity problem in the context of models with a finite dimensional commodity space in the capital theory context non convexities have received explicit treatment in a few papers in two distinguishable ways the problem is cast either in a discrete time framework aoki 1971 rothschild 1971 or in a continuous time framework in which there are implicitly unbounded economies of scale in investment the latter formulation leads to jumps in the state variable or lumpy investment the standard problem treated is one of decreasing costs in the installation of new capacity contributions include chenery 1952 dixit mirrlees and stern 1975 hartwick 1976 manne 1967 srinivasan 1967 starrett 1978 and weitzman 1970 these types of analysis unfortunately ignore some of the most interesting problems associated with non convexities in investment theory in a discrete time framework the important distinction between stocks and flows is blurred while the capacity installation problem by admitting unbounded scale economies excludes the smoothing of state variables that follows by allowing for eventually increasing costs of adjustment in this paper we undertake a systematic examination of non convexities or sometimes non concavities in the context of a classic problem in continuous time investment theory the optimal accumulation of capital by a firm maximizing its present value over an infinite horizon while the results obtained are specific to this particular model we feel that they can be qualitatively extended to any capital theory problem which can be cast in a continuous time optimal control theory framework there are various sorts of non2 convexities which can arise in these problems first there can be either stock or flow non convexities that is non convexities which are introduced into the net benefit function the measure of the flow of benefits at each moment through changes in the capital stock state variable on the one hand or changes in the flow of investment control variable on the other if the benefit and transition functions are not concave in both these variables then necessary conditions are no longer sufficient for optimality and conventional marginal analysis fails non convexities can also be introduced into the value functional which has a stock dimension in order to examine these different sorts of non convexity problems we shall now present the basic economic problem a firm is faced with the problem of maximizing the present value of discounted cash flow over an infinite horizon hence it chooses an investment programme i t to maximize 00

along the way back from the brink abstract an optimal control model of wildlife management is developed to analyze the transitory dynamics set forth by the reintroduction of animals that provide benefits but can also come into conflict with humans the shadow price of these resources can be positive or negative potentially creating a nonconvexity the conditions under which reintroduction is not desirable are determined and those characterizing the initiation of costly population control are investigated an application to deer management illustrates the relevance of the nonconvexity and the magnitude of losses stemming from delays in implementing optimal management the impact of distributional concerns on efficiency is discussed

rent seeking for pure public goods in this paper we present a formal analysis of rent seeking for public goods by two or more groups with different numbers of individuals we begin by considering equally wealthy groups under risk neutrality a case which constitutes our basic model several surprising and interesting results emerge from the analysis of this basic case the problem is then extended to deal with a groups with different wealth levels and b risk aversion this last extension brings about a further crop of interesting and useful results

interest rates exchange rates and present value models of the current account this paper develops a testable intertemporal model of the current account that allows for variable interest rates and exchange rates these additional variables are channels through which external shocks may influence the domestic current account the restrictions from the theoretical model are subjected to present value tests using quarterly data from three small open economies the paper finds that including the interest rate and exchange rate improves the fit of the intertemporal model over what was found in previous studies the model predictions better replicate the volatility of current account data and better explain historical episodes of current account imbalance

the contribution of economic fundamentals to movements in exchange rates starting from the asset pricing approach of engel and west we examine the degree to which fundamentals can explain exchange rate fluctuations we show that it is not possible to obtain sharp inferences about the relative contribution of fundamentals using only data on observed monetary fundamentals money minus output differentials across countries and exchange rates we use additional data on interest rate and price differentials along with the implications of the monetary model of exchange rates to decompose exchange rate fluctuations in general we find that money demand shifts along with observed monetary fundamentals are an important contributor to exchange rate fluctuations

tinbergen and tipping points could some thresholds be policy induced abstract thresholds and tipping points that are characteristic of dynamic multi stability are increasingly prominent touchstones of the science policy interface prior economic work has shown thresholds arising in convex concave ecological models that exclude humans may disappear in models of coupled economic ecological systems when economic agents are included as part of the system less well understood is how this result may depend on the ability of humans to manage complex systems we examine the role of institutions that condition the available management choices we find institutional restrictions do not generate non convexities when the ecological system is well behaved but that these restrictions may generate non convexities when the ecological system is convex concave these results are tied to the concept of path controllability which is when managers have sufficient controls to guide the system across the state space path controllability is the dynamic version of the tinbergen rule and generally requires separate controls to manage each possible ecological externality we link the concepts of ecosystem externalities thresholds and path controllability to provide new economic insights into problems with the potential for multi stability and we illustrate the importance of institutions for managing convex concave systems

equilibrium structure in an economic model of conflict four different types of equilibrium are possible within a two player model of society where only armed self enforcement of property rights is possible the main underlying parameters are the total resource endowment and the initial distribution of this endowment between the players the parameter space is partitioned into regions in which the respective types of equilibrium occur the equilibrium types involve positive arms expenditure by respectively neither player the richer player and both players the latter case involves a sub type in which the poorer player s entire endowment is expended on arms jel d30 d72 d74