Evolutionary stability and Nash equilibrium in finite populations, with an application to price competition

Schaffer (1988) proposed a concept of evolutionary stability for finite-population models that has interesting implications in economic models of evolutionary learning, since it is related to perfectly competitive equilibrium. The present paper explores the relation of this concept to Nash equilibrium in particular classes of games, including constant-sum games, games with weak payoff externalities, and games where imitative decision rules are individually improving. An illustration of the latter is provided in the context of Bertrand oligopoly with homogeneous product which allows for a characterization of the set of evolutionarily stable prices.

The Open Method of Coordination (OMC) as an Evolutionary Learning Process

We interpret the Open Method of Coordination (OMC), recently adopted by the EU as a mode of governance in the area of social policy and other fields, as an imitative learning dynamics of the type considered in evolutionary game theory. The best-practise feature and the iterative design of the OMC correspond to the behavioral rule "imitate the best." In a redistribution game with utilitarian governments and mobile welfare beneficiaries, we compare the outcomes of imitative behavior (long-run evolutionary equilibrium), decentralized best-response behavior (Nash equilibrium), and coordinated policies. The main result is that the OMC allows policy coordination on a strict subset of the set of Nash equilibria, favoring in particular coordination on intermediate values of the policy instrument

The Open Method of Coordination (OMC) as an Evolutionary Learning Process

We interpret the Open Method of Coordination (OMC), recently adopted by the EU as a mode of governance in the area of social policy and other fields, as an imitative learning dynamics of the type considered in evolutionary game theory. The best-practise feature and the iterative design of the OMC correspond to the behavioral rule “imitate the best.” In a redistribution game with utilitarian governments and mobile welfare beneficiaries, we compare the outcomes of imitative behavior (long-run evolutionary equilibrium), decentralized best-response behaviour (Nash equilibrium), and coordinated policies. The main result is that the OMC allows policy coordination on a strict subset of the set of Nash equilibria, favoring in particular coordination on intermediate values of the policy instrument.Open Method of Coordination, Finite-population Evolutionarily Stable Strategy, imitation, mobility, redistribution

The Open Method of Coordination (OMC) as an Evolutionary Learning Process

We interpret the Open Method of Coordination (OMC), recently adopted by the EU as a mode of governance in the area of social policy and other fields, as an imitative learning dynamics of the type considered in evolutionary game theory. The best-practise feature and the iterative design of the OMC correspond to the behavioral rule "imitate the best." In a redistribution game with utilitarian governments and mobile welfare beneficiaries, we compare the outcomes of imitative behavior (long-run evolutionary equilibrium), decentralized best-response behavior (Nash equilibrium), and coordinated policies. The main result is that the OMC allows policy coordination on a strict subset of the set of Nash equilibria, favoring in particular coordination on intermediate values of the policy instrument.Open Method of Coordination; Finite-population Evolutionarily Stable Strategy; Imitation; Mobility; Redistribution.

The Open Method of Coordination (OMC)

We interpret the Open Method of Coordination (OMC), recently adopted by the EU as a mode of governance in the area of social policy and other ¯elds, as an imitative learning dynamics of the type considered in evolutionary game theory. The best-practise feature and the iterative design of the OMC correspond to the behavioral rule \imitate the best." In a redistribution game with utilitarian gov- ernments and mobile welfare bene¯ciaries, we compare the outcomes of imitative behavior (long-run evolutionary equilibrium), decentralized best-response behavior (Nash equilibrium), and coordinated policies. The main result is that the OMC allows policy coordination on a strict subset of the set of Nash equilibria, favoring in particular coordination on intermediate values of the policy instrument.

The Asset Market Game

This paper models asset markets as a game where assets pay according to an arbitrary payoff matrix,investors decide on fractions of wealth to allocate to each asset,and prices result from market clearing. The only pure-strategy Nash equilibrium is to split wealth proportionally to the assets´expected returns, which can be interpreted as investing according to the fundamentals. Further, the equilibrium is evolutionarily stable in the sense of Schaffer (1988). We also study the stability properties of the equilibrium in an evolutionary dynamics where wealth flows with higher probability into those strategies that obtain higher realized payoffs.

The Evolutionary Logic of Feeling Small

In a (generalized symmetric aggregative game, payoffs depend only on individual strategy and an aggregate of all strategies. Players behaving as if they were negligible would optimize taking the aggregate as given. We provide evolutionary and dynamic foundations for such behavior when the game satisfies supermodularity conditions. The results obteined are also useful to characterize evolutionarily stable strategies in a finite population.

- AN EVOLUTIONARY MODEL OF BERTRAND OLIGOPOLY

We analyze the long-run outcome of markets in which boundedly rational firms with a decreasingreturns to scale technology compete in prices. The behavior of these firms is based on limitation ofsuccess and experimentation. In this framework, we introduce a new approach to model boundedlyrational behavior, based on the idea of behavioral principles, i.e. formal descriptions. Even with thesimplest ones, the result is that the prices announced are a strict refinement of the set of Nashequilibria. With more sophisticated behavioral principles, the long-run outcome corresponds to theconcept of central prices (wich are also Nash equilibria) introduced here. This is a robust andclear-cut prediction wich, under quadratic costs and arbitrary demand, essentially coincides with theWalrasian equilibrium.evolution, mutation, imitation

An Evolutionary Analysis of Insurance Markets

Since the seminal work by Rothschild and Stiglitz on competitive insurance markets under adverse selection the problem of non-existence of equilibrium has puzzled many economists. In this paper we approach this problem from an evo- lutionary point of view. In a dynamic model insurance companies remove loss- making contracts from the market and copy prot-making ones. Occasionally, they also experiment, adding new contracts or removing current ones arbitrarily. We show that the Rothschild-Stiglitz outcome arises in the long run if it consti- tutes an equilibrium in the static framework, but also if it is not an equilibrium, provided that rms only experiment with contracts in the vicinity of their current portfolio.