A randomized algorithm for finding frequent elements in streams using O(log log N) space

Masatora Ogata, Yukiko Yamauchi, Shuji Kijima, Masafumi Yamashita

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Citations (Scopus)

Abstract

Finding frequent items in a data stream is a fundamental problem; Given a threshold θ ε (0,1), find items appearing more than θ·N times in an input stream with length N. Karp, Shenker, Papadimiriou (2003) gave a simple deterministic online algorithm, which allows false positive outputs using memory of O(θ -1 log N) bits, while they also gave a lower bound. Motivated by the theoretical bound of the space complexity, this paper proposes a simple randomized online algorithm using memory of O(θ -2 log 2 θ -1+log log N) bits where parameters for approximation are hidden in the constant. Our algorithm is robust for memory overflow, compared with other naïve randomized algorithms, or deterministic algorithms using memory of O(logN) bits. We also give some randomized algorithms for approximate counting.

Original languageEnglish
Title of host publicationAlgorithms and Computation - 22nd International Symposium, ISAAC 2011, Proceedings
Pages514-523
Number of pages10
DOIs
Publication statusPublished - Dec 26 2011
Event22nd International Symposium on Algorithms and Computation, ISAAC 2011 - Yokohama, Japan
Duration: Dec 5 2011Dec 8 2011

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume7074 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Other

Other22nd International Symposium on Algorithms and Computation, ISAAC 2011
CountryJapan
CityYokohama
Period12/5/1112/8/11

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • Computer Science(all)

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    Ogata, M., Yamauchi, Y., Kijima, S., & Yamashita, M. (2011). A randomized algorithm for finding frequent elements in streams using O(log log N) space. In Algorithms and Computation - 22nd International Symposium, ISAAC 2011, Proceedings (pp. 514-523). (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 7074 LNCS). https://doi.org/10.1007/978-3-642-25591-5_53