This paper studies Stackelberg price competition in a multi-sided market. The second-mover can engage in divide-and-conquer strategies, which involve cross-subsidies between sides. The paper recovers bounds on profits, and refines the results with a selection criteria whereby consumers resolve...

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...

We introduce a model in which firms trade goods via bilateral contracts which specify a buyer, a seller, and the terms of the exchange. This setting subsumes (many-to-many) matching with contracts, as well as supply chain matching. When firms' relationships do not exhibit a supply chain...

We study learning in a setting where agents receive independent noisy signals about the true value of a variable and then communicate in a network. They naïvely update beliefs by repeatedly taking weighted averages of neighbors' opinions. We show that all opinions in a large society converge to...

The actions of different agents sometimes reinforce each other. Examples are network effects and the threshold models used by sociologists as well as (Harvey) Leibenstein's "bandwagon effects." We model such situations as a game with increasing differences, and show that tipping of equilibria,...

We study optimal contracting in team settings where agents have many opportunities to shirk, task-level monitoring is needed to provide useful incentives, and it is difficult to write individual performance into formal contracts. Incentives are provided informally, using wasteful sanctions like...