S. Mehdi Tashakkori Hashemi
Faculty of Mathematics and Computer Science,
Amirkabir University of Technology,
424 Hafez Ave, 15914 Tehran, IRAN

Email: hashemi@aut.ac.ir
            s.m.tashakkori@gmail.com
Tel:   +9821 64542522
         +9821 66406322
Fax: +9821 66497930