Economic Theory, Econometrics, and Mathematical Economics: A Series of Monographs and Textbooks: Noncooperative Approaches to the Theory of Perfect Competition focuses on the application of noncooperative approaches to the theory of perfect competition, including Cournot game, no-surplus condition, and Nash equilibria. The selection first elaborates on collusive behavior in noncooperative epsilon-equilibria of oligopolies with long but finite lives and noncooperative price taking in large dynamic markets. Discussions focus on noncooperative equilibria which support the monopoly allocation, alternative definition of perfect epsilon-equilibrium, one-period Cournot game, fixed-demand case, and replication case. The book takes a look at noncooperative price taking in large dynamic markets, no-surplus condition as a characterization of perfectly competitive equilibrium, perfect competition, profit criterion, and the organization of economic activity. Topics include profits to individually improving welfare, structure of firms, competitive allocations as no surplus allocations, profits as rents, Walrasian and perfectly competitive equilibrium, and no-surplus and core equivalence as alternative characterizations of perfectly competitive equilibrium. The manuscript ponders on Nash equilibria of market games and efficiency properties of strategic market games, as well as commodities, agents, assignments, strategic markets games, proper and full Cournot-Nash equilibria, and finiteness and inefficiency. The selection is a valuable source of data for researchers interested in noncooperative approaches to the theory of perfect competition.

A "folk theorem" originating, among others, in the work of Stiglitz maintains that competitive equilibria area always or "generically" inefficient (unless contracts directly specify consumption levels as in Prescott and Townsend, thus bypassing trading in anonymous markets). This paper critically reevaluates these claims in the context of a general equilibrium economy with moral hazard. We first formalize this folk theorem. Firms offer contracts to workers who choose an effort level that is private information and that affects worker productivity. The clarify the importance of trading in anonymous markets, we introduce a monitoring partition such that employment contracts can specify expenditures over subsets in the partition, but cannot regulate how this expenditure is subdivided among the commodities within a subset. We say that preferences are nonseparable (or more accurately, not weakly separate) when the marginal rate of substitution across commodities within a subset in the partition depends on the effort level, and that preferences are weakly separate when there exists no such subset. We prove that the equilibrium is always inefficient when a competitive equilibrium allocation involves less than full insurance and preferences are nonseparable. This result appears to support the conclusion of the above-mentioned folk theorem. Nevertheless, our main result highlights its limitations. Most common-used preference structures do not satisfy the nonseparability condition. We show that when preferences are weakly separable, competitive equilibria with moral hazard are constrained optimal, in the sense that a social planner who can monitor all consumption levels cannot improve over competitive allocations. Moreover, we establish epsilon-optimality when there are only small deviations from weak separability. These results suggest that considerable care is necessary in invoking the folk theorem about the inefficiency of competitive equilibria with private information. Keywords: competitive equilibrium, double deviations, efficiency, general equilibrium theory, monitoring partition, moral hazard. JEL Classifications: D52, D61, D62, D82.

Theory of incompl. markets/M. Magill, M. Quinzii. - V.1.

This monograph is a systematic exposition of the authors' research on general equi librium models with an infinite number of commodities. It is intended to serve both as a graduate text on aspects of general equilibrium theory and as an introduction, for economists and mathematicians working in mathematical economics, to current research in a frontier area of general equilibrium theory. To this end, we have pro vided two introductory chapters on the basic economic model and the mathematical framework. The exercises at the end of each section complement the main exposition. Chapter one is a concise but substantiative discussion of the questions of exis tence and optimality of competitive equilibria in the Walrasian general equilibrium model of an economy with a finite number of households, firms and commodities. Our extension of this model to economies with an infinite number of commodities constitutes the core material of this book and begins in chapter three. Readers fa miliar with the Walrasian general equilibrium model as exposited in [13], [23J or [52J may treat chapter one as a handy reference for the main economic concepts and notions that are used throughout the book.