My expertise is the development, to prove existence and the computation of equilibria in economic and game theoretic models. In particular models in economics, including auctions, are studied with indivisible commodities like houses, cars, computers, that can not be divided in arbitrary amounts. The existence of equilibria in such models is mathematically very complicated. Further new solution concepts ate developed for cooperative games in which the possibilities for players to cooperate are limited and refinements of existing solution concepts for noncooperative games are proposed. These problems can be very often described as a system of equations, of which the solution is the required solution concept.

• Emeritus Professor, Dept. of Econometrics and Operations Research and CentER, Tilburg University, July 2018 - present
• Full Professor in Game Theory and Equilibrium Programming, Dept. of Econometrics and Operations Research and CentER, Tilburg University, July 1996 - July 2018
• Extraordinary Professor, Dept. of Econometrics and CentEER, Tilburg University, April 1990 - July 1996
• Associate Professor, Dept. of Econometrics and CentER, Tilburg University, January 1986 - March 1990
• Assistant Professor, Dept. of Econometrics, Tilburg University, June 1981 - December 1985
• Visiting lecturer, Yale School of Organization and Management, and visiting professor, Cowles Foundation for Research in Economics, Yale University, New Haven, Connecticut, U.S.A., August 1980 - May 1981
• Research Associate, Dept. of Actuarial Sciences and Econometrics, Free University, Amsterdam, August 1976 - July 1980
• Research Assistant, Dept. of Econometrics, State University Groningen, September 1975 - July 1976