Before the talk, participants may find it useful to familiarise themselves with the basic features of the proof, to be found in the preprint.
____________________________________________________________________________ S Barry Cooper Tel: UK: (0113) 233 5165, Int: +44 113 233 5165 School of Mathematics Fax: UK: (0113) 233 5145, Int: +44 113 233 5145 University of Leeds Email: s.b.cooper@leeds.ac.uk Leeds LS2 9JT Home tel: (0113) 278 2586, Int: +44 113 278 2586 U.K. WWW: http://www.amsta.leeds.ac.uk/~pmt6sbc ____________________________________________________________________________