\centerline{\bf Contributors} \medskip \noindent Contributors to this edition, without whom etc., include: {\obeylines Tom Blyth Dept of Mathematics University of St Andrews North Haugh St Andrews KY16 9SS |pmstb@st-and.savb| \medskip Sebastian Rahtz Dept of Electronics and Computer Science Southampton University Southampton SO9 5NH |spqr@soton.cm| \medskip Laurie Benfield Computing Centre University of East Anglia Norwich NR4 7TJ |s050@uea.cpc865| \medskip Barbara Beeton American Mathematical Society PO Box 6248 Providence RI 02940 |bnb@xx.lcs.mit.edu| |bb@sail.stanford.edu| \medskip David Brightly Daresbury Lab Keckwick Lane Warrington WA4 4AD |brightly@daresbury| \medskip Joan Smith, {\sc sobemap} 17 Tansa Road London NW3 2UA tel: 01 435 9300 \medskip Bijan Djahansouzi Dept of Aeronautics Imperial College London SW7 2BP }