1. School of Mathematics, Iran University of Science and Technology, Tehran 13114-16846, Iran
2. Department of Mathematics, Faculty of Civil Engineering, Slovak University of Technology in Bratislava, Radlinského 11, 810 05 Bratislava, Slovakia
3. Institute of Information Theory and Automation, The Czech Academy of Sciences, Pod Vodárenskou věží 4, 182 08 Praha, Czech Republic
4. Department of Mathematics, Faculty of Mathematical Sciences, Shahid Beheshti University, Tehran 19839-69411, Iran