Jonathan
G. Campbell
School of Computer Science,
The Queen's University of
Belfast,
Belfast, BT7 1NN.
email: jg.campbell@qub.ac.uk
URL:http://www.cs.qub.ac.uk/~J.Campbell/csc722/
Report No:
jc/00/0005/r
Revision 4.0
Date: 12th November 2000