I investigate complementarity games played on graphs, which model negative externalities embedded in structures of interaction. On the complete graph, the traditional economic analysis applies: the number of agents playing one strategy is proportional to its payoff. I show that, in general and...

This study explores the formation of buyer-seller relationships in markets with observable quality. We develop a model that explains why relationships form in equilibrium within such markets. A key feature of our model is that as individuals gain experience in the marketplace, they resolve...

This paper studies the dynamics of fundamental research. We develop a simple model where researchers allocate their effort between improving existing fields and inventing new ones. A key assumption is that scientists derive utility from recognition from other scientists. We show that the economy...

This paper considers the formation of risk-sharing networks. Following empirical findings, we build a model where risk-sharing takes place between pairs of individuals. We ask what structures emerge when pairs can agree to form links, but people cannot coordinate links across a population. We...

Many environmental policies including the Kyoto Protocol, the Acid Rain Program, the Montreal Protocol and the phase-out of leaded gas are designed to achieve a target level of abatement within a specified period of time. This paper examines how pollution abatement should be allocated over time...

We model network formation when heterogeneous nodes enter sequentially and form connections through both random meetings and network-based search, but with type-dependent biases. We show that there is "long-run integration," whereby the composition of types in sufficiently old nodes'...

We study a setting in which individual players choose their partners as well as a mode of behavior in 2 x 2 anti-coordination games -- games where a player's best response is to behave differently than the opponent. We characterize the nature of equilibrium networks as well as study the effects...