In this paper, I consider the problem of optimal unemployment insurance in a world in which the unemployed agent's job-finding effort is unobservable and his level of savings is unobservable. I show that the first-order approach is not always valid for this problem, and I argue that the...

In this paper, we demonstrate that it may be socially optimal for countries to have different currencies, even though they have no possibility of independently controlling their money supplies. We assume that agents have heterogeneous preferences over goods of different national origin, and that...