We develop a theory of price discrimination in many-to-many matching markets in which agents’ preferences are vertically and horizontally differentiated. The optimal plans induce negative assortative matching at the margin: agents with a low value for interacting with other agents are included...

A frequently heard explanation for the underdeveloped metro system in Rome is the following one: If we tried to build a new metro line, it would probably be stopped by archeological finds that are too valuable to destroy, so the investment would be wasted. This statement, which seems...

We present a model where society is partitioned into groups, or communities, whose preferences may conflict. In particular, the actions of members of a certain group can inflict negative spillovers on members of other groups. We show that, on one hand, coordination at the group-level may be...

We employ a three-stage game model with cost-reducing research and development (R&D) that is subject to spillovers to consider the problem of excess entry under free-entry equilibrium relative to the social optimum. Firms choose to enter or exit a market in the first stage, choose R&D in the...