Optimal harvesting of a spatial renewable resource

In this paper we investigate the optimal harvesting of a renewable natural resource. While in most standard approaches the resource is located at a single point, we allow the resource to be distributed spatially. Consequently, an agent who exploits the resource has to travel from one location to another. For a fixed planning horizon, we investigate the speed and the path of harvesting chosen by the agent. We show that the agent adjusts this speed so as to visit each location only once, even in the absence of travelling cost. Since the agent does not return to any location for a second harvest, it is optimal to fully deplete the resource upon arrival. A similar type of bang–bang solution results when we drop the assumption of a constant harvesting rate: allowing for a variable harvesting rate, the agent chooses to fully exploit the resource either in the last or in the first travelling period. A society interested in conserving some of the resource thus has to take measures to limit the exploitative behaviour of the agent.     

Positive welfare effects of trade barriers in a dynamic partial equilibrium model

We develop a simple two-region, cobweb-type dynamic partial equilibrium model to demonstrate the existence of optimal, possibly non-zero, trade barriers. A pure comparative statics analysis of our model suggests that a reduction of trade barriers, modeled as small but positive import tariffs, always enhances welfare. However, taking a dynamic perspective reveals that nonlinear trade interactions between two regions may generate endogenous price fluctuations which can hamper welfare. Finally, we allow special interest groups, such as consumers or producers from these two regions, to lobby for a particular level of trade barriers. Our model predicts that time-varying trade barriers may be another channel for market instability.     

Optimal dividend strategies with time-inconsistent preferences

This paper studies the optimal dividend strategies of an insurance company when the manager has time-inconsistent preferences. We consider the problem for a naive manager and a sophisticated manager, and analytically derive the optimal dividend strategies when claim sizes follow an exponential distribution. Our results show that the manager with time-inconsistent preferences tends to pay out dividends earlier than her time-consistent counterpart and that the sophisticated manager is more inclined to pay out dividends than the naive manager. Furthermore, we extend these results to the case with claim sizes following a mixed exponential distribution, and provide a numerical analysis to reveal the sensitivity of the optimal dividend strategies to changes in the premium, claims and surplus volatility.     

The optimal treatment of tax expenditures

This paper analyzes the optimal treatment of tax expenditures. It develops an optimal tax model where individuals derive utility from spending on a “contribution” good such as charitable giving. The contribution good has also a public good effect on all individuals in the economy. The government imposes linear taxes on earnings and on the contribution good so as to maximize welfare. The government may also finance directly the contribution good out of tax revenue. Optimal tax and subsidy rates on earnings and the contribution good are expressed in terms of empirically estimable parameters and the redistributive tastes of the government. The optimal subsidy on the contribution good is increasing in the size of the price elasticity of contributions, the size of the crowding out effect of public contributions on private contributions, and the size of the public good effect of the contribution good. Numerical simulations show that the optimal subsidy on contributions is fairly sensitive to the size of these parameters but that, in most cases, it should be lower than the earnings tax rate.     

Dynamic advertising and pricing with constant demand elasticities

In this paper we analyze a stochastic dynamic advertising and pricing model with isoelastic demand. The state space is discrete, time is continuous and the planing horizon is allowed to be finite or infinite. A dynamic version of the Dorfman–Steiner identity will be derived. Explicit expressions of the optimal advertising and pricing policies, of the value function and of the optimal advertising expenditures will be given. The general results will be used to analyze the case of impatient customers. Furthermore, particular time inhomogeneous models and homogeneous ones with and without discounting will be examined. We will study the social efficiency of a monopolist's optimal policies and the consequences of specific subsidies. From a buyer's perspective, our analysis reveals that waiting – when looking at (immediate) expected prices – is never profitable should two or more units be available. But we will also prove that the sequence of average sales prices is monotone decreasing. Moreover, the techniques applied to solve the discrete stochastic advertising and pricing problem will be used to solve a related deterministic control problem with continuous state space.     

Energy balance climate models and general equilibrium optimal mitigation policies

In a general equilibrium model of the world economy, we develop a two-dimensional energy balance climate model featuring heat diffusion and anthropogenic forcing driven by global fossil fuel use across the sphere of the Earth. This introduces an endogenous location dependent temperature function, driving spatial characteristics, in terms of location dependent damages resulting from local temperature anomalies into the standard climate-economy framework. We solve the social planner's problem and characterize the competitive equilibrium for two polar cases differentiated by the degree of market integration. We define optimal taxes on fossil fuel use and how they may implement the planning solution. Our results suggest that if the implementation of international transfers across latitudes is not possible then optimal taxes are in general spatially non-homogeneous and may be lower at poorer latitudes. The degree of spatial differentiation of optimal taxes depends on heat transportation. By employing the properties of the spatial model, we show by numerical simulations how the impact of thermal transport across latitudes on welfare can be studied.     

定西地区农业生态系统结构优化的对策

本文通过定西地区农业生态系统结构与功能分析，认为：生态系统结构不完善，生产力和经济功能低下。据此从农业可持续发展的角度出发，提出了优化农业生态系统结构和提高其功能的对策。     

Escalating penalties for repeat offenders: a note on the role of information

The severity of the sanction for a given offense is often determined by the offense history of the offender. We establish that this policy can be welfare-maximizing if individuals are imperfectly informed about the magnitude of the sanction. Imperfect information distorts individuals’ perception of the expected sanction of the first offense. Once detected, individuals learn about the sanction applicable to their act, making this argument less relevant for consecutive offenses.      

Tax reform and collective family decision-making

Traditional analysis of tax reform treats market behaviour as arising out of individual utility maximisation. In this paper, behaviour is modelled as the Pareto-efficient outcome of a family decision process. Conditions for the existence of a feasible, Pareto-improving tax change are presented and contrasted with those that obtain in the individualistic case. The consequences of treating households as a single individual are also discussed.     

The role of externalities and information aggregation in market collapse

We examine the role that belief, network externality, and information aggregation play in inefficient market collapses. After receiving consecutive negative shocks, some ex-ante identical Bayesian agents will be discouraged about the unknown state of the market they invest; therefore, they will stop investing. This decision will have two effects: first, it will cause agents to aggregate information through social/observational learning; second, it will decrease the network externality effect. We show that there might be an inefficient market collapse if the externality effect diminishes too much, and the cost of re-entry to the market is too high. We also analyze the effects of strategic delay and experimentation on the exit decision of the agents. I especially thank Thomas D. Jeitschko, Matthew Mitchell, B. Ravikumar Ted Temzelides. I also thank anonymous referees, an associate editor, John Conlon, Larry Samuelson, Troy Tassier, Stephen Williamson, and seminar participants of the University of Saskatchewan, Georgia Tech, Concordia University, University of Manitoba, Iowa Alumni Workshop, Midwest Economic Theory Conferences held at Indiana Bloomington, and Notre Dame, and 1st International Conference on Business, Management and Economics organized by Yasar University.