Title
Deterministic extractors for small-space sources
Abstract
We give polynomial-time, deterministic randomness extractors for sources generated in small space, where we model space s sources on (0,1)n as sources generated by width 2s branching programs: For every constant δ0, we can extract .99 δ n bits that are exponentially close to uniform (in variation distance) from space s sources of min-entropy δ n, where s=Ω(n). In addition, assuming an efficient deterministic algorithm for finding large primes, there is a constant η 0 such that for any δn-η, we can extract m=(δ-δ)n bits that are exponentially close to uniform from space s sources with min-entropy δ n, where s=Ω(β3 n). Previously, nothing was known for δ ≤ 1/2, even for space 0.Our results are obtained by a reduction to a new class of sources that we call independent-symbol sources, which generalize both the well-studied models of independent sources and symbol-fixing sources. These sources consist of a string of n independent symbols over a d symbol alphabet with min-entropy k. We give deterministic extractors for such sources when k is as small as polylog(n), for small enough d.
Year
DOI
Venue
2011
10.1016/j.jcss.2010.06.014
J. Comput. Syst. Sci.
Keywords
DocType
Volume
exponentially close,model space,n bit,small-space source,randomness extractors,pseudorandomness,algorithm extracts m,deterministic extractor,deterministic randomness extractor,markov chains,bit-fixing sources,samplable sources,independent sources,small space,variation distance,branching program,markov chain,polynomial time
Journal
77
Issue
ISSN
ISBN
1
Journal of Computer and System Sciences
1-59593-134-1
Citations 
PageRank 
References 
31
1.21
32
Authors
4
Name
Order
Citations
PageRank
Jesse Kamp11378.60
Anup Rao258132.80
Salil P. Vadhan34676234.84
David Zucherman42588266.65