1. Department of InformaticsUniversity of Western Macedonia Kastoria Greece
2. Department of EconomicsUniversity of Western Macedonia Kastoria Greece
3. Department of Mathematics, College of SciencesKing Saud University P. O. Box 2455, Riyadh 11451 Saudi Arabia
4. Group Leader, Group of Modern Computational MethodsUral Federal University 620002, 19 Mira Street Ekaterinburg Russian Federation
5. Section of Mathematics, Department of Civil EngineeringDemocritus University of Thrace Xanthi Greece