Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site watmath.UUCP Path: utzoo!watmath!mwang From: mwang@watmath.UUCP (mwang) Newsgroups: ont.events Subject: UW Theory Seminar, Dr. Zaks on "On the Bit Complexity of Distributed Computations in a Unidirectional Ring with a Leader" Message-ID: <16282@watmath.UUCP> Date: Tue, 27-Aug-85 09:48:25 EDT Article-I.D.: watmath.16282 Posted: Tue Aug 27 09:48:25 1985 Date-Received: Wed, 28-Aug-85 21:24:12 EDT Expires: Thu, 5-Sep-85 00:00:00 EDT Organization: U of Waterloo, Ontario Lines: 50 DEPARTMENT OF COMPUTER SCIENCE UNIVERSITY OF WATERLOO SEMINAR ACTIVITIES THEORY SEMINAR - Wednesday, September 4, 1985. Dr. S. Zaks of Technion will speak on ``On the Bit Com- plexity of Distributed Computations in a Unidirectional Ring with a Leader.'' TIME: 3:30 PM ROOM: MC 6091A (Please Note) ABSTRACT We study the bit complexity of pattern recognition in a distributed unidirectional ring with a leader. Each processor gets as input a letter from some alphabet, and these concatenated letters, starting at the leader, form the pattern of the ring. The leader initiates an algorithm that accepts or rejects this pattern. Thus each algorithm recognizes a language over a given alphabet. We prove the following for a ring of size n: - (1) A language is recognized by an algorithm that uses O(n) bits if and only if it is regular (also com- - - pared is the bit complexity vs. the number of rounds). (2) Every non-regular language requires at least ()(nlogn) bits for its recognition (clearly, any -- - - language requires no more than O(n**2) bits for its - --- recognition). (3) For every function g(n), - - ()(nlogn) < g(n) < O(n**2), there is a language -- - - - - - - - --- that requires O(g(n)) bits for its recognition. - - - August 19, 1985