First Author:   Hossein Hassani Cardiff University HassaniH@cf.ac.uk   Cardiff, CF24 4AG, UK   07703367456(Phone) 07703367456(Fax) Second Author: Anatoly Zhigljavsky Cardiff University ZhigljavskyAA@cf.ac.uk   School of Mathematics, Cardiff University,, Senghennydd Road, Cardiff CF24 4AG, UK Cardiff, CF24 4AG, UK       http://http://www.cf.ac.uk/maths/subsites/zhigljavskyaa/index.html