1. Department of Economics, The Hebrew University of Jerusalem, Mount Scopus 91905, Jerusalem, Israel; and Department of Economics, University of Leicester, Leicester LE1 7RH, United Kingdom
2. Departamento de Economía Cuantitativa, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain
3. Department of Mathematics, Universidade da Coruña, 15071 A Coruña, Spain