Nearly Optimal Pseudorandomness From Hardness
Existing proofs that deduce \text{BPP} =\mathrm{P} from circuit lower bounds convert randomized algorithms into deterministic algorithms with a large polynomial slowdown. We convert randomized algorithms into deterministic ones with little slowdown. Specifically, assuming exponential lower bounds ag...
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| Published in: | Proceedings / annual Symposium on Foundations of Computer Science pp. 1057 - 1068 |
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| Main Authors: | , , , |
| Format: | Conference Proceeding |
| Language: | English |
| Published: |
IEEE
01.11.2020
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| Subjects: | |
| ISSN: | 2575-8454 |
| Online Access: | Get full text |
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| Summary: | Existing proofs that deduce \text{BPP} =\mathrm{P} from circuit lower bounds convert randomized algorithms into deterministic algorithms with a large polynomial slowdown. We convert randomized algorithms into deterministic ones with little slowdown. Specifically, assuming exponential lower bounds against randomized single-valued nondeterministic (SVN) circuits, we convert any randomized algorithm over inputs of length n running in time t\geq n to a deterministic one running in time t^{2+\alpha} for an arbitrarily small constant \alpha > 0 . Such a slowdown is nearly optimal, as, under complexity-theoretic assumptions, there are problems with an inherent quadratic derandomization slowdown. We also convert any randomized algorithm that errs rarely into a deterministic algorithm having a similar running time (with pre-processing). The latter derandomization result holds under weaker assumptions, of exponential lower bounds against deterministic SVN circuits. Our results follow from a new, nearly optimal, explicit pseudorandom generator fooling circuits of size s with seed length (1 + α)log s, under the assumption that there exists a function f ∊ E that requires randomized SVN circuits of size at least 2 (1−α')n , where. α=O(α'). The construction uses, among other ideas, a new connection between pseudoentropy generators and locally list recoverable codes. |
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| ISSN: | 2575-8454 |
| DOI: | 10.1109/FOCS46700.2020.00102 |