(until early 1998) Professor David E. Evans, Professor of Mathematics, Department of Mathematics, University of Wales, Swansea, Singleton Park, Swansea, SA2 8PP, WALES. Tel: +44 1792 295460; fax: +44 1792 295843; email: David.E.Evans@swansea.ac.uk (from early 1998) Mathematics Institute, University of Wales, Cardiff, Senghennydd Road, Cardiff CF2 4YH Tel: +44 1222 874827; fax: +44 1222 874199 Professor Yasuyuki Kawahigashi, Associate Professor, Department of Mathematical Sciences, University of Tokyo, Komaba, Tokyo, 153, JAPAN. Tel: +81 3 5465 7024; fax: +81 3 5465 7012; email: yasuyuki@ms.u-tokyo.ac.jp
