Rabah Amir

Noncooperative versus cooperative R&D with endogenous spillover rates

This paper deals with a general version of a two-stage model of R&D and product market competition. We provide a thorough generalization of previous results on the comparative performance of noncooperative and cooperative R&D, dispensing in particular with ex-post firm symmetry and linear demand assumptions. We also characterize the structure of profit-maximizing R&D cartels where firms competing in a product market jointly decide R&D expenditure, as well as internal spillover, levels. We establish the firms would essentially always prefer extremal spillovers, and within the context of a standard specification, derive conditions for the optimality of minimal spillover.

Entry, exit, and imperfect competition in the long run

An infinite-horizon, stochastic model of entry and exit with sunk costs and imperfect competition is constructed. Simple examples provide insights into: (1) the relationship between sunk costs and industry concentration, (2) entry when current profits are negative, and (3) the relationship between entry and the length of the product cycle. A subgame perfect Nash equilibrium for the general dynamic stochastic game is shown to exist as a limit of finite-horizon equilibria. This equilibrium has a relatively simple structure characterized by two numbers per finite history. Under very general conditions, it tends to exhibit excessive entry and insufficient exit relative to a social optimum.

Strategic intergenerational bequests with stochastic convex production

SummaryThis note reconsiders the well-known model of strategic bequest/ altruistic growth, but with stochastic production satisfying a strong convexity condition: The probability that the next stock exceeds any given level is concave in investment. Existence of a Markov-stationary equilibrium consumption schedule, which is continuous and with all slopes in [0,1], is established. Under smooth data and interiority assumptions, this schedule is differentiable, and marginal consumption is in (0,1). This property allows for a rigorous and straightforward treatment of the equilibrium characterization problem.

Complementarity and diagonal dominance in discounted stochastic games

We consider discounted stochastic games characterized by monotonicity, supermodularity and diagonal dominance assumptions on the reward functions and the transition law. A thorough novel discussion of the scope and limitations of this class of games is provided. Existence of a Markov-stationary equilibrium for the infinite-horizon game, proved by Curtat (1996), is summarized. Uniqueness of Markov equilibrium and dominance solvability of the finite-horizon game are established. In both cases, the equilibrium strategies and the corresponding value functions are nondecreasing Liptschitz-continuous functions of the state vector. Some specific economic applications are discussed.

STOCHASTIC GAMES IN ECONOMICS AND RELATED FIELDS: AN OVERVIEW

This survey provides an extensive account of research in economics based on the stochastic games paradigm. Its area-by-area coverage is in the form of an overview, and includes applications in resource economics, industrial organization, macroeconomics, market games, experimental and empirical economics. For methodologically defined frameworks, the coverage is somewhat more detailed (to the extent that the material is not covered elsewhere in this volume), and includes the open-loop concept, the linear-quadratic model, myopic equilibrium, games of perfect information, and stochastic games with a continuum of players.

DEMAND-INDUCED ENDOGENOUS PRICE LEADERSHIP

This paper provides general conditions on the direct demand functions in a Bertrand duopoly with differentiated substitute products and constant marginal costs, that allow an unambiguous ranking of firms equilibrium payoffs between sequential play (with both order of moves) on the one hand, and simultaneous play on the other. The main results are that (i) when prices are strategic complements, both firms prefer sequential moves (with either order) to simultaneous moves, (ii) when prices are strategic substitutes, both firms prefer simultaneous moves to moving second in sequential play, and (iii) in the mixed strategic substitute/complement case, one firm is as in (i) and the other as in (ii). Thus, sequential moves would plausibly endogenously emerge in cases (i) and (iii), with one specified leader in the latter case. The analysis relies crucially on the theory of supermodular games, and is conducted at a high level of generality, dispensing with concavity-type assumptions, and taking into account both the issues of existence and possible non-uniqueness of the different equilibria involved.

Monopoly versus R&D-integrated duopoly

In the standard two-stage framework of R&D/product market competition, this paper provides a performance comparison between monopoly and the cartelized research joint venture, using two well-known models based on different versions of the R&D spillover process. According to the model with a wider scope of application, monopoly always leads to a higher propensity for R&D and, when R&D costs are low, to the best overall market performance. The results also allow for a comparison between the two underlying models of strategic R&D.

Asymmetric Regulation of Identical Polluters in Oligopoly Models

Studies of second-b est environmental regulation ofiden tical polluting agents have invariably ignored potentially welfare-improving asymmetric regulation by imposing equal regulatory treatment of identical firms at the outset. Yet, cost asymmetry between oligopoly firms may well give rise to private as well as social gains. A trade-off is demonstrated for the regulator, between private costs savings and additional social costs when asymmetric treatment is allowed. Asymmetry is indeed optimal for a range of plausible parameter values. Further, it is demonstrated that for a broad class of abatement cost functions, there is scope for increasing welfare while keeping both total output and total emission constant. Some motivating policy issues are discussed in light ofthe results, including international harmonization and global carbon dioxide reduction.

Stochastic games in economics: the lattice-theoretic approach

This chapter considers a recent trend in the application of stochastic games to economics characterized by the use of the lattice-theoretic approach to capture the monotonic properties of Markovian equilibria. The topics covered are: (i) a general framework for discounted stochastic games with Liptchitz-continuous and monotone equilibrium strategies and values, (ii) a model of capital accumulation, (iii) two classes of games with perfect information, in strategic bequests and oligopoly with commitment. In view of the restriction to pure-strategy equilibria and of the natural monotonicity property of strategies and value functions in most economic applications, this approach appears most promising.

STOCHASTIC VERSION OF POLTEROVICH'S MODEL: EXPONENTIAL TURNPIKE THEOREMS FOR EQUILIBRIUM PATHS

The paper examines a stochastic analogue of the Polterovich model of economic dynamics. The study focuses on the asymptotic properties of equilibrium paths. The main results are stochastic turnpike theorems with exponential estimates of the convergence rate.