IEEE Copyright notice

© 1998, IEEE. Published in the Proceedings of FOCS'98, 
8-11 November 1998 in Palo Alto, CA.  Personal use of 
this material is permitted. However, permission to 
reprint/republish this material for advertising or promotional 
purposes or for creating new collective works for resale or 
redistribution to servers or lists, or to reuse any copyrighted 
component of this work in other works, must be obtained from the 
IEEE. Contact: Manager, Copyrights and Permissions / IEEE Service 
Center / 445 Hoes Lane / P.O. Box 1331 / Piscataway, NJ 
08855-1331, USA. Telephone:  + Intl. 732-562-3966.