Martinez-Legaz, J.-. & Santos, M.S. Econ Theory (1993) 3: 335. doi:10.1007/BF01212921
This paper develops a duality theory for preference orders, and highlights important differences with respect to the cardinal utility approach. Our main result is a symmetric duality theorem, under the minimal hypotheses, between direct and indirect preferences. In contrast to the cardinal theory, we also find that these conditions do not completely characterize the class of indirect preference orders.