Path: utzoo!utgpu!water!ylfink From: ylfink@water.waterloo.edu (ylfink) Newsgroups: ont.events,uw.talks Subject: Non-Oblivious Hashing. Keywords: Dr. Jeanette P. Schmidt, Tues., June 7/88, 3:30 PM, DC 1302. Message-ID: <1613@water.waterloo.edu> Date: 3 Jun 88 19:22:24 GMT Distribution: ont Organization: U of Waterloo, Ontario Lines: 46 DEPARTMENT OF COMPUTER SCIENCE UNIVERSITY OF WATERLOO SEMINAR ACTIVITIES DATA STRUCTURING SEMINAR - Tuesday, June 7, 1988 Dr. Jeanette P. Schmidt, Courant Institute, New York University, will speak on ``Non-Oblivious Hashing''. TIME: 3:30 PM ROOM: DC 1302 ABSTRACT Non-oblivious hashing, where the information gathered by performing ``unsuccessful'' probes determines the probe strategy, is introduced and used to obtain the following results for static lookup on full tables: a) An O(1) worst case scheme that requires only - logarithmic additional memory (improving on the linear space upper bound). b) An almost sure O(1) probabilistic worst case - scheme, without any additional memory (improving on previous logarithmic time upper bounds). c) Enhancements to hashing: Solving a) and b) in the multikey record environment, search can be performed under any key in time O(1); finding - the nearest neighbor, the rank, etc. in logarithmic time. Our non-oblivious upper bounds are much better than the appropriate oblivious lower bounds. June 3, 1988