The paper develops a technique for studying incentive problems with unidimensional hidden characteristics in a way that is independent of whether the type set is nite, the type distribution has a continuous density, or the type distribution has both mass points and an atomless part. By this...

The paper develops a version of Pontryagin's maximum principle for optimal control problems with monotonicity constraints on control variables. Whereas the literature handles such constraints by imposing an assumption of piecewise smoothness on the control variable and treating the slope of this...

The paper provides a new formulation of the Mirrlees-Seade theorem on the positivity of the optimal marginal income tax, under weaker assumptions and in a more general model. The formulation of the theorem is independent of whether the model involves finitely many types or a continuous type...

The paper provides a new proof of the positivity of the optimal marginal income tax, in a more general model, under weaker assumptions. The analysis focusses on the (weakly) relaxed problem in which upward incentive constraints are replaced by a monotonicity condition on consumption. Without...

The paper analyses the causes of the current crisis of the global financial system, with particular emphasis on the systemic elements that turned the crisis of subprime mortgage-backed securities in the United States, a small part of the overall system, into a worldwide crisis. The first half of...

This paper studies the design of optimal utilitarian mechanisms for an excludable public good. Excludability provides a basis for making people pay for admissions; the payments can be used for redistribution and/or funding. Whereas previous work assumed that admissions are governed by the...