Explicit two-source extractors and resilient functions
Explicit two-source extractors and resilient functions
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DOI:
10.4007/annals.2019.189.3.1
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发表时间:
2019-05-01
影响因子:
4.9
通讯作者:
Zuckerman, David
中科院分区:
文献类型:
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作者:
Chattopadhyay, Eshan;Zuckerman, David
We explicitly construct an extractor for two independent sources on n bits, each with min-entropy at least log(C) n for a large enough constant C. Our extractor outputs one bit and has error n(-Omega(1)). The best previous extractor, by Bourgain, required each source to have min-entropy .499n.A key ingredient in our construction is an explicit construction of a monotone, almost-balanced Boolean function on n bits that is resilient to coalitions of size n(1-delta) for any delta > 0. In fact, our construction is stronger in that it gives an explicit extractor for a generalization of non-oblivious bit-fixing sources on n bits, where some unknown n - q bits are chosen almost polylog(n)-wise independently, and the remaining q = n(1-delta) bits are chosen by an adversary as an arbitrary function of the n - q bits. The best previous construction, by Viola, achieved q = n(1/2-delta).Our explicit two-source extractor directly implies an explicit construction of a 2((log log N)O(1)) Ramsey graph over N vertices, improving bounds obtained by Barak et al. and matching an independent work by Cohen.