The diffusion of an innovation can be represented by a process in which agents choose perturbed best responses to what their neighbors are currently doing.  Diffusion is said to be fast if the expected waiting time until the innovation spreads widely is bounded above independently of the size...

We show that a combination of temporariness and spending pressure is intrinsic to the aid relationship.  In our analysis, recipients rationally discount the pronouncements of donors about the duration of their commitments because in equilibrium they know that some donors will honor those...

A long-standing open question raised in the seminal paper of Kalai and Lehrer (1993) is whether or not the play of a repeated game, in the rational learning model introduced there, must eventually resemble play of exact equilibria, and not just play of approximate equilibria as demonstrated...

This paper studies uniqueness of equilibrium in symmetric 2 x 2 bayesian games.  It shows that if signals are highly but not perfectly dependent then players play their risk-dominant actions for all but a vanishing set of signal realizations.  In contrast to the global games literature, noise...

Stochastic learning models provide sharp predictions about equilibrium selection when the noise level of the learning process is taken to zero.  The difficulty is that, when the noise is extremely small, it can take an extremely long time for a large population to reach the stochastically...

This paper defines regular and weakly regular equilibria for monotone Bayesian games with one-dimensional actions and types.  It proves an index theorem and provides applications to uniqueness of equilibrium.  It also provides analyses of stability with respect to perturbations and dynamic...

This paper studies the extent to which diffusion approximations provide a reliable guide to equilibrium selection results in finite games. It is shown that they do for a class of finite games with weak learning provided that limits are taken in a certain order. The paper also shows that making...

A rational player will never play a strictly dominated strategy. It might be tempting therefore to eliminate such strategies from any subsequent analysis. However, if equilibrium selection is an issue it may be wrong to do so. In models of adaptive learning with state-independence mutations,...

It is common to model costs of carrying out strategies in games in relation to the complexity, in some sense, of the strategies. We show a particularly general definition of complexity for this purpose, one that subsumes many alternatives as special cases. We explore how this definition can be...

Ultimatum games have been extensively used in experimental studies. By studying the consequences that restrictions shared by ultimatum games have in subject`s behaviour, this paper argues that some results are falsified by design constraints. This paper also presets a taxonomy of certification,...