For several decades, scholars have developed methods for solving optimization problems which emerge in economics, econometrics, operations research, and other disciplines. A considerable effort has been made to construct equations from which constraints can be derived, but surprisingly little...

For any linear transformation and two convex closed sets, we provide necessary and sufficient conditions for when the transformation of the intersection of the sets coincides with the intersection of their images. We also identify analogous conditions for non-convex sets, general...

We solve the problem of a social planner who seeks to minimize inequality via transfers with a fixed public budget in a distribution of exogenously given incomes. The appropriate solution method depends on the objective function: If it is convex, as in the case of the absolute mean deviation, it...