We consider the spread of a harmful state through a population divided into two groups. Interaction patterns capture the full spectrum of assortativity possibilities. We show that a central planner who aims for eradication optimally either divides equally the resources across groups, or...

This paper studies the effect of social learning on political outcomes in a model of informative campaign advertising. Voters' communication network affects parties' incentives to disclose political information, voters' learning about candidates running for office, and polarization of the...

This article studies mergers in markets where firms invest in a portfolio of research projects of different profitability and social value. The investment of a firm in one project imposes both a negative business-stealing and a positive business-giving externality on the rival firms. We show...