1986-1992 Assistant Professor of Economics, VPI & SU. 1992-1997 Associate Professor of Economics, VPI & SU. 1997-Present Professor of Economics, VPI & SU. other occupations 1979 Visiting Assistant, Department of Mathematics, University of Nice (France). 1979-80 Research Fellow, Department of Mathematics, University of Rennes (France). 1980-84 Research StaÆ, Department of Economics, University of Bonn (Germany). 1982-83 Visiting Scholar, Department of Economics, Harvard University (Cambridge, MA). 1984-85 Assistant, Department of Economics, University of Mannheim (Germany). Fall 1985 Research StaÆ, Department of Economics, University of Bonn (Germany). Fall 1990 Research Fellow, CentER at Tilburg University (Netherlands). Fall 1994 Visiting Professor, Institute for Advanced Studies (Vienna, Austria). Spring 1995 Senior Research Fellow, CentER at Tilburg University (Netherlands). Fall 2002 Visiting Professor, Institute of Economics, University of Copenhagen (Denmark). Winter 2003 Visiting Professor, Institute for Advanced Studies (Vienna, Austria). Summer 2003 Mercator Professor, Alfred-Weber-Institut, University of Heidelberg (Germany). 2011-12 Guest Professor, ETH Zurich (Switzerland)