1. Rikio Ichishima:
Department of Sport and Physical Education, Faculty of Physical Education, Kokushikan Universityty, 7-3-1 Nagayama, Tama-shi, Tokyo,Japan
2. Francesc A. Muntaner-Batle:
Graph Theory and Applications Research Group, School of Electrical Engineering and Computer Science, Faculty of Engineering and Built Environment,The University of Newcastle, NSW 2308, Australia
3. Akito Oshima:
Graph Theory and Applications Research Group, School of Electrical Engineering and Computer Science, Faculty of Engineering and Built Environment,The University of Newcastle, NSW 2308, Australia