1. Mathematical Institute of the Serbian Academy of Sciences Knez Mihailova 36/III Belgrade 11000 Serbia
2. Department of Medical ResearchChina Medical University Hospital, China Medical University Taichung 40402 Taiwan Republic of China
3. Department of Computer Science and Information EngineeringAsia University 500 Lioufeng Rd., Wufeng Taichung 41354 Taiwan Republic of China