Affiliation: | (1) Institute of Applied Mathematics, Middle East Technical University, 06531 Ankara, Turkey;(2) Faculty of Arts and Sciences, Department of Mathematics, Suleyman Demirel University, 32 260 Isparta, Turkey;(3) Department of Mathematics, University of Lleida, C/Jaume II 69, 25001 Lleida, Spain;(4) Center and Department of Econometrics and OR, Tilburg University, P. O. Box 90153, 5000LE Tilburg, The Netherlands |