منابع مشابه
On Average Time Hierarchies
For a time-constructible function T we give an explicit language LT which can be recognized in time T (n). We prove that any Turing machine that recognizes LT requires time close to T (n) for most inputs, thus forming an average time hierarchy. The existence of the average time hierarchy was known, but depended on languages de ned by complicated diagonalization. We also give simple proofs for t...
متن کاملOn Heuristic Time Hierarchies Preliminary Version
We study the existence of time hierarchies for heuristic algorithms. We prove that a time hierarchy exists for heuristics algorithms in such syntactic classes as NP and coNP, and also in semantic classes AM and MA. Earlier, Fortnow and Santhanam (FOCS’04) proved the existence of a time hierarchy for heuristics algorithms in BPP. We present an alternative approach and give a simpler proof.
متن کاملTime-Dependent Contraction Hierarchies
Contraction hierarchies are a simple hierarchical routing technique that has proved extremely efficient for static road networks. We explain how to generalize them to networks with time-dependent edge weights. This is the first hierarchical speedup technique for timedependent routing that allows bidirectional query algorithms. For large realistic networks with considerable time-dependence (Germ...
متن کاملTime Hierarchies: A Survey
We survey time hierarchies, with an emphasis on recent work on hierarchies for semantic classes.
متن کاملHeuristic Time Hierarchies via Hierarchies for Sampling Distributions
We give a new simple proof of the time hierarchy theorem for heuristic BPP originally proved by Fortnow and Santhanam [FS04] and then simplified and improved by Pervyshev [Per07]. In the proof we use a hierarchy theorem for sampling distributions recently proved by Watson [Wat13]. As a byproduct we get that P 6⊆ BPTime[nk] if one way functions exist. As far as we know this statement was not kno...
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ژورنال
عنوان ژورنال: Journal of Computer and System Sciences
سال: 1979
ISSN: 0022-0000
DOI: 10.1016/0022-0000(79)90028-x