computational complexity

, Volume 14, Issue 3, pp 186–227

Compression of Samplable Sources

Open Access
Original Paper

Abstract.

We study the compression of polynomially samplable sources. In particular, we give efficient prefix-free compression and decompression algorithms for three classes of such sources (whose support is a subset of {0, 1}n).
  1. 1.

    We show how to compress sources X samplable by logspace machines to expected length H(X) + O(1).

     
Our next results concern flat sources whose support is in P.
  1. 2.

    If H(X) ≤ k =  n − O(log n), we show how to compress to expected length k + polylog(nk).

     
  2. 3.

    If the support of X is the witness set for a self-reducible NP relation, then we show how to compress to expected length H(X) + 5.

     

Keywords.

Expander graphs arithmetic coding randomized logspace pseudorandom generators approximate counting 

Subject classification.

68P30 

Copyright information

© Birkhäuser Verlag, Basel 2005

Authors and Affiliations

  1. 1.Computer Science DivisionU.C. BerkeleyBerkeleyU.S.A
  2. 2.Division of Engineering and Applied SciencesHarvard UniversityCambridgeU.S.A
  3. 3.Department of Computer ScienceUniversity of TexasAustinU.S.A

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