Equilibrium for Overlapping Generations in Continuous Time

We prove the existence of general equilibrium for continuous-time overlapping-generations models. Previous theorems exclude all non-linear C.E.S. and von Neumann–Morgenstern preferences and exclude production. Our primitive assumptions are satisfied by such preferences and by all Markovian production technologies satisfying Bewley's assumptions for Arrow–Debreu models provided that storage is possible, at some finite rate of depreciation and some positive capacity. A non-existence example shows our Markovian and storage assumptions cannot be dropped.Journal of Economic LiteratureClassification Numbers: C62, D51, D90.     

An Anti-folk Theorem in Overlapping Generations Games with Limited Observability

We study the effect of limited observability on the possibility of cooperation in a simple overlapping generations model. If new entrants can observe only the recent history of the game, then cooperation cannot be sustained for certain classes of games. Journal of Economic Literature Classification Numbers: C72, D82.     

Determinacy of Equilibrium in an Overlapping Generations Model with Heterogeneous Agents

We study the determinacy of perfect foresight equilibrium near a steady state in an overlapping generations model with production and both altruistic and non-altruistic agents having distinct utility functions. The proportion of each type of consumer is exogenously given. Our main results show that when there are positive stationary bequests, some standard assumptions on preferences and technology rule out local indeterminacy for any positive value of the proportions. In the particular case of a separable utility function for altruistic agents, we prove that the determinacy property does not depend on the size of the “infinite lived” altruistic dynasties. Journal of Economic Literature Classification Numbers: C62, D91, O21, O41.     

纯交换OLG经济中的习惯类型与经济的动态性质

在OLG的纯交换经济中,区分了内部习惯和外部习惯对经济动态性质的影响。我们发现内部习惯增加了年轻人的储蓄并可以把古典经济转变为萨谬尔森经济;外部习惯减少了年轻人的储蓄并可以把萨谬尔森经济转变为古典经济。不论是外部习惯还是内部习惯,都提高了在相对风险规避系数一定的情况下消费者忍受风险的能力,从而可能导致经济的周期运动。     

Learning and Equilibrium Selection in a Monetary Overlapping Generations Model with Sticky Prices

We study adaptive learning in a monetary overlapping generations model with sticky prices and monopolistic competition for the case where learning agents observe current endogenous variables. Observability of current variables is essential for informational consistency of the learning setup with the model setup but generates multiple temporary equilibria when prices are flexible and prevents a straightforward construction of the learning dynamics. Sticky prices overcome this problem by avoiding simultaneity between prices and price expectations. Adaptive learning then robustly selects the determinate (monetary) steady state independent from the degree of imperfect competition. The indeterminate (non-monetary) steady state and non-stationary equilibria are never stable. Stability in a deterministic version of the model may differ because perfect foresight equilibria can be the limit of restricted perceptions equilibria of the stochastic economy with vanishing noise and thereby inherit different stability properties. This discontinuity at the zero variance of shocks suggests one should analyse learning in stochastic models.     

Equilibrium Determinacy under Monetary and Fiscal Policies in an Overlapping Generations Model

This paper studies the issue of equilibrium determinacy under monetary and fiscal policy feedback rules in an optimizing general equilibrium model with overlapping generations and flexible prices. It is shown that equilibria may be determinate also when monetary and fiscal policies are both 'passive'. In particular, under passive monetary rules, equilibrium uniqueness is more likely to be verified when fiscal policies are less committed to public debt stabilization.     

A Stochastic Overlapping Generations Economy with Inheritance

An overlapping generations model of an exchange economy with two sources of uncertainty is considered. Individuals have a finite expected life span and uncertain annual income. Conditions concerning birth, death, inheritance and bequests are fully specified. Under such conditions, the existence of a stationary Markovian equilibrium is established in some generality, and several explicitly solvable examples are examined in detail. Received August 6, 2001; revised version received March 12, 2002 Published online: November 11, 2002     

Time and Uncertainty in Overlapping Generations Economies

This paper shows the general reversibility of every perfect foresight equilibrium of an overlapping generations economy. It then shows and characterizes the existence of reversible sunspot equilibria in these economies as well, which seems to be at odds with our intuition about the irreversibility of a tree of events. Although the paper establishes also that such reversible stochastic equilibria constitute a negligible subset of all the equilibria of their class, their mere existence may be considered somewhat puzzling for this intuition. Journal of Economic Literature Classification Numbers: D50, D80, D90.     

Cooperation in an Overlapping Generations Experiment

Recent theoretical work shows that folk theorems can be developed for infinite overlapping generations games. Cooperation in such games can be sustained as a Nash equilibrium. But, of course, there are other equilibria. This paper investigates experimentally whether cooperation actually occurs in a simple overlapping generations game. Subjects both play the game and formulate strategies. Our main finding is that subjects fail to exploit the intertemporal structure of the game. Even when we provided subjects with a recommendation to play the grim trigger strategy, most of the subjects still employed safe history-independent strategies. Journal of Economic Literature Classification Numbers: C72, C92, D90.     

Fiscal Policy in an Overlapping Generations Model with Bequest-as-Consumption

This paper analyzes an overlapping generation (OLG) growth model wherein saving finances second period consumption and bequest‐as‐consumption. First, it looks at the market equilibrium and at the optimal solution; then it turns to the issue of decentralizing the optimal solution with various taxes and transfers. Depending on the available instruments, either a first‐best or a second‐best optimum can be achieved. Throughout the paper, the results are contrasted with those obtained in the standard OLG model without intergenerational transfers.     

A Neo-Ricardian Trade Model with Overlapping Generations*

This paper develops and examines a discrete-time two-by-two-by-two barter trading world which incorporates populations. composed of overlapping, life-cycle-maximizing generations; each provides an economically distinguishable factor of production. It is shown that free trade without compensation can be Pareto inferior to autarky for one country. Conditions for uncompensated free trade to take place under a majority voting system are derived. The model permits intergenerational borrowing and lending to take place domestically but not internationally.     

Altruism and Determinacy of Equilibria in Overlapping Generations Models with Externalities

This paper deals with an OLG model with production and a single commodity, in which agents are assumed altruistic and the aggregate production function contains external effects. I prove that, if the technology satisfies a minor assumption, which encompasses positive and negative externalities, some curvature conditions on the utility function ensure local determinacy of stationary and period 2 equilibria. I prove that non-separable, strictly concave preferences are a fundamental ingredient for the occurrence of indeterminate equilibria. Finally, considering the case of unbounded growth, I establish that for any utility and production functions a unique balanced growth path is globally determinate.
JEL Classification Numbers: C62, E32     

The Under-Exploitation of Natural Resources: A Model with Overlapping Generations*

It is well known that competitive markets may fail to generate an optimal rate of extraction of a natural resource-stock. The barrier to optimality may be uncertainty about tenure, commonality of property rights in the resource, or uncertainty about the extent of the resource. In all these cases, suboptimality takes the form of over-extraction. We draw attention to an additional source of suboptimality. In an economy with overlapping generations, the resource-stock plays the double role of repository of savings and source of productive inputs. The decline in the supply of the resource-stock may eventually force its price so high that it ceases to perform its second function. Extraction comes to an end even though the resource has a positive marginal productivity in producing consumption goods. This is inefficient, hence suboptimal. This time, however, suboptimality takes the form of under-extraction.     

An Overlapping Generations Model of Climate-Economy Interactions

A numerically calibrated overlapping generations model of climate change and the world econommy is examined in this paper. In the absence of intergenerational transfers, efficient rates of greenhouse gas emissions abatement rise from 16% in the present to 25% in the long run, while mean global temperature increases by 7.4°C relative to the preindustrial norm. A utilitarian optimum, which attaches equal weight to each generation's life-cycle utility, yields abatement rates that rise from 48% to 89%, with a long-run temperature increase of 3.4°C. A second-best utilitarian path, in which intergenerational transfers are by assumption institutionally infeasible, also supports stringent abatement measures.     

Capital Accumulation in a Stochastic Overlapping Generations Model with Social Security

This paper analyzes the impact of pay-as-you-go financed social security on the stochastic process for the capital stock in a stochastic overlapping generations model. It is shown that the probability distribution of the capital stock in absence of social security dominates that in a pay-as-you-go system in the sense of stochastic dominance. Furthermore, the study demonstrates that the sufficient conditions ensuring the existence and uniqueness of stationary equilibria in a pay-as-you-go system are more restrictive than in the model without social security. Journal of Economic Literature Classification Numbers: C62, H55.     

Implementing Steady State Efficiency in Overlapping Generations Economies with Environmental Externalities

We consider in this paper overlapping generations economies with pollution resulting from both consumption and production. The competitive equilibrium steady state is compared to the optimal steady state from the social planner's viewpoint. We show that the dynamical inefficiency of a competitive equilibrium steady state with capital–labor ratio exceeding the golden rule ratio still holds. Moreover, the range of dynamically efficient steady state capital ratios increases with the effectiveness of the environment maintenance technology, and decreases for more polluting production technologies. We characterize some tax and transfer policies that decentralize as a competitive equilibrium outcome the transition to the social planner's steady state.     

Efficiency and Lack of Commitment in an Overlapping Generations Model with Endowment Shocks

This paper considers a pure exchange stochastic overlapping generations model in which, on each date, an economy faces an aggregate endowment shock. On each date, a young agent and an old agent simultaneously decide how much of their respective endowments to transfer to the other agent; however, a young agent cannot make promises about how much he or she will give when old. In this sense, an economy faces a limited commitment constraint. This paper characterizes an efficient intergenerational risk sharing allocation that satisfies a limited commitment constraint, and also studies the role of money and history in a stochastic overlapping generations economy.     

Capital Taxation, Tobin's q and Overlapping Generations

This study examines the effect of capital taxation on the long-term equilibrium in an intertemporal model, incorporating overlapping generations of the Blanchard–Weil type and value-maximizing firms with adjustment costs in investment. I demonstrate that an increase in capital taxation raises the steady-state expected lifetime utility of an agent born after the tax increase, provided the intergenerational redistribution effect achieved through lowering the rate of return is greater than that achieved through the tax revenue effect owing to the reduced capital–labour ratio, and that an increased ITC rate would not necessarily raise the steady-state lifetime utility of all agents.
JEL Classification Numbers: D91, D92, E62, H24, H25.     

Extensive Form Games with Uncertainty Averse Players

Nash equilibrium presumes that the beliefs of a player are represented by a probability measure. Motivated by the Ellsberg Paradox and relevant experimental findings demonstrating that this representation of beliefs may be unrealistic, this paper generalizes Nash equilibrium in finite extensive form games to allow for preferences conforming to the multiple priors model developed by Gilboa and Schmeidler [Journal of Mathematical Economics, 18 (1989), 141–153]. The implications of this generalization for strategy choices and welfare are studied. Journal of Economic Literature Classification Numbers: C72, D81.