1 Department of Mathematics and Computer Science, University of Catania, Italy
2 The Bucharest University of Economic Studies, Romania
3 IMUVA, Universidad de Valladolid, Spain
4 Institute of Applied Mathematical Research, Karelia Research Center of Russian
5 Academy of Sciences, Russia
6 Saint-Petersburg State University, Russia
7 University of Porto, Portugal, and LIAAD, INESC TEC
8 Department of Mathematics, University of Evora, Portugal
9 Poznan University of Technology, Poland
10 Affiliation: IAM, METU, Ankara
11 Graduate School of Management (GSOM)