I owe a debt to many of my colleagues and friends for their helpful comments and suggestions during the development of this and the previous version. Among these special thanks go to Warwick DEA people for their generous help. I also warmly thank the many visitors who have forwarded suggestions to me based on their experience with earlier edition of this page.
I would like to thanks Prof Emmanuel Thanassoulis who introduced me to the world of DEA and Prof Robert G. Dyson for his support and encouragements in the early development of the DEAzone.