1. Université Paris Diderot, Sorbonne Paris Cité, Laboratoire Jacques-Louis Lions, Paris, France
2. Federal Reserve Bank of Chicago, Chicago, IL 60604, USA
3. Department of Mathematics, University Dauphine, 75017 Paris, France
4. Collège de France, 75005 Paris France
5. Department of Economics, Princeton University, Princeton, NJ 08544, USA