We use cumulative reaction functions to compare long-run market structures in aggregative oligopoly games. We first compile an IO toolkit for aggregative games. We show strong neutrality properties across market structures. The aggregator stays the same, despite changes in the number of firms...

We investigate how liability rules and property rules affect the incentives to invest in research tools. We argue that it is hard to deter infringement under any of the enforcement regimes available. However, counterintuitively, a credible threat of infringement can actually be beneficial to the...

Incorporating space in economic models has two important consequences. First, the hypothesis of perfect competition becomes untenable, and second, the distinction between private and public goods becomes blurred. We review arguments that lead to these conclusions and summarize recent work...