Optimism and Pessimism in Games.

This paper considers the impact of ambiguity in strategic situations. It extends the earlier literature by allowing for optimistic responses to ambiguity. Ambiguity is modelled by CEU preferences. We study comparative statics of changes in ambiguity-attitude in games with strategic complements or substitutes. This gives a precise statement of the impact of ambiguity on economic behaviour. We also the possibility that players may be overconfident in the sense of over-estimating the probability of favourable outcomes. This has a similar effect of increasing equilibrium strategies in games of strategic complements, Finally we consider RDEU preferences.Ambiguity in games, overcon?fidence, strategic complementarity, optimism, RDEU.

Sequential Two-Player Games with Ambiguity

If players' beliefs are strictly non-additive, the Dempster-Shafer updating rule can be used to define beliefs off the equilibrium path. We define an equilibrium concept in sequential two-person games where players update their beliefs with the Dempster-Shafer updating rule. We show that in the limit as uncertainty tends to zero, our equilibrium approximates Bayesian Nash equilibrium by imposing context-dependent constraints on beliefs under uncertainty.

Ambiguity

Ambiguity refers to a decision situation under uncertainty when there is incomplete information about the likelihood of events. Different formal models of this notion have been developed with differing implications about the representation of ambiguity and ambiguity aversion.uncertainty, ambiguity, ambiguity attitude

Market distortions and corporate governance.

This paper studies corporate governance when a firm operates in imperfect markets. We derive firms' decisions from utility maximisation by individuals. This reduces the usual monopoly distortion. Corporate governance can effect the equilibrium in the product (or input) markets. This enables us to endogenise the objective function of the firm. If the firm cannot commit not to change its constitution, we find a Coase-like result where all market power is lost in the limit. We present a more abstract model of governance in the presence of market distortions and discuss its implications for the governance of universities.corporate governance, stakeholder, strategic delegation, economics of universities.

Optimism and Pessimism in Games

This paper considers the impact of ambiguity in strategic situations. It extends the earlier literature by allowing for optimistic responses to ambiguity. Ambiguity is modelled by CEU preferences. We propose a new solution concept for players who may express ambiguity- preference. Then we study comparative statics of changes in ambiguity-attitude in games with strategic complements. This gives a precise statement of the impact of ambiguity on economic behaviour.Ambiguity in games, support, strategic complementarity, optimism, multiple equilibria.

Ambiguity

Ambiguity refers to a decision situation under uncertainty when there is incomplete information about the likelihood of events. Different formal models of this notion have been developed with differing implications about the representation of ambiguity and ambiguity aversion.

The Arbitrage Pricing Theorem with Incomplete Preferences

This paper proves existence of equilibrium and the arbitrage pricing theorem for an asset exchange economy, where the individual's preferences may be incomplete or intransitive. This extends existing results to a more general set of individual preferences. We also prove the arbitrage pricing theorem for a theory of choice under uncertainty by Bewley [1986]. These preferences model Knightian uncertainty by allowing for the possibility that preferences are incomplete.Incomplete Preferences, Equilibrium Existence, Arbitrage Pricing Theorem, Knightian Uncertainty

Externalities, Monopoly and the Objective Function of the Firm

This paper provides a theory of general equilibrium with externalities and/or monopoly. We assume that the firm's decisions are based on the preferences of shareholders and/or other stakeholders. Under these assumptions, a firm will produce fewer negative externalities than the comparable profit maximizing firm. In the absence of externalities, equilibrium with a monopoly will be Pareto efficient if the firm can price discriminate. The equilibrium can be implemented by a 2-part tariff.Externality, general equilibrium, 2-part tariff, objective function of the firm.

How productive is optimism? the Impact of ambiguity on the "big push"

The paper finds that sufficient ambiguity leads to the uniqueness of equilibrium in macroeconomic coordination games. The results have a Keynesian flavour: sufficient optimism gives rise to a Pareto-optimal equilibrium; and sufficient pessimism results in a Pareto-inferior equilibrium. This analysis is applied to a "Big Push" model from the economic growth literature.Ambiguity, Strategic Complementary, Coordination Games, Optimism, "Big Push".

Are the Treasures of Game Theory Ambiguous?

Goeree & Holt (2001) observe that, for some parameter values, Nash equilibrium provides good predictions for actual behaviour in experiments. For other payoff parameters, however, actual behaviour deviates consistently from that predicted by Nash equilibria. They attribute the robust deviations from Nash equilibrium to actual players’ considering not only marginal gains and losses but also total pay-offs. In this paper, we show that optimistic and pessimistic attitudes towards strategic ambiguity may induce such behaviour.