Ronald Jones's duality analysis as a foundation for applied general‐equilibrium modeling

Ronald Jones made seminal contributions to general‐equilibrium theory, moving away from an emphasis on the existence of equilibrium to algebraic formulations which enabled us to characterize key relationships between parameters and variables, such as that between tariffs and domestic factor prices and welfare. But the analysis remained limited in value for policy evaluation: the analysis was local, it provided only qualitative results, it was limited to very small models, and strictly interior solutions had to be assumed. The contribution of this paper is largely pedagogic and methodological. I show how the tools and approach pioneered by Jones can be generalized via the use of duality, complementarity and the Karush–Kuhn–Tucker theorem into a global, quantitative analysis of large changes in high‐dimensional models which also allows for regime changes and corner solutions. I then show how the resulting nonlinear complementarity problem directly translates into a numerical model using the General Algebraic Modeling System (GAMS).