Mean field games (MFG) are dynamic games with infinitely many infinitesimal agents. In this joint work with C. Rainer, we study the efficiency of Nash MFG equilibria: Namely, we compare the social cost of an MFG equilibrium with the minimal cost a global planner can achieve. We find a structure condition on the problem under which there exists efficient MFG equilibria and, in case this condition is not fulfilled, quantify how inefficient MFG equilibria are.

Joint work with Catherine Rainer. Speaker(s): Pierre Cardaliaguet (Paris Dauphine)