Tight bounds for depth-two superconcentrators

  • Jaikumar Radhakrishnan*
  • , Amnon Ta-Shma
  • *Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

25 Scopus citations

Abstract

The minimum size of a depth-two N-superconcentrator is shown to be Θ(N log2 N/log log N). For the upper bound, superconcentrators are developed by putting together a small number of disperser graphs. which are obtained using a probabilistic argument. Two different methods are presented to show the lower bounds. The first method shows that superconcentrators contain several disjoint disperser graphs. When combined with the lower bound for disperser graphs due to the method Kovari, Sos and Turan, this gives an almost optimal lower bound of Ω(N(log N/log log N)2) on the size of N-superconcentrators. The second method, based on the work of Hansel, gives the optimal lower bound.

Original languageEnglish
Title of host publicationAnnual Symposium on Foundations of Computer Science - Proceedings
PublisherIEEE Comp Soc
Pages585-594
Number of pages10
ISBN (Print)0818681977
DOIs
StatePublished - 1997
Externally publishedYes
EventProceedings of the 1997 38th IEEE Annual Symposium on Foundations of Computer Science - Miami Beach, FL, USA
Duration: 20 Oct 199722 Oct 1997

Conference

ConferenceProceedings of the 1997 38th IEEE Annual Symposium on Foundations of Computer Science
CityMiami Beach, FL, USA
Period20/10/9722/10/97

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