منابع مشابه
Uniformly Hard Languages
Ladner [18] showed that there are no minimal recursive sets under polynomial-time reductions. Given any recursive set A, Ladner constructs a set B such that B strictly reduces to A but B does not lie in P. The set B does have very long sequences of input lengths of easily computable instances. We examine whether Ladner’s results hold if we restrict ourselves to “uniformly hard languages” which ...
متن کاملOn Small Hard Leaf Languages
This paper deals with balanced leaf language complexity classes, introduced independently in [1] and [14]. We propose the seed concept for leaf languages, which allows us to give “short” representations for leaf words. We then use seeds to show that leaf languages A with NP ⊆ BLeaf (A) cannot be polylog-sparse (i.e. censusA ∈ O(log )), unless PH collapses. We also generalize balanced ≤ m -reduc...
متن کاملMeasure, Stochasticity, and the Density of Hard Languages
Ogiwara and Watanabe have recently shown that the hypothesis P not equal NP implies that no (polynomially) sparse language is polynomial-time btt-hard for NP. Their technique does not appear to allow significant relaxation of either the query bound or the sparseness criterion. It is shown here that a stronger hypothesis --namely, that NP does not have measure 0 in exponential time --implies the...
متن کاملComplete distributional problems, hard languages, and resource-bounded measure
We say that a distribution μ is reasonable if there exists a constant s ≥ 0 such that μ({x | |x| ≥ n}) = Ω( 1 n s ). We prove the following result, which suggests that all DistNP-complete problems have reasonable distributions. If NP contains a DTIME(2n)-bi-immune set, then every DistNP-complete set has a reasonable distribution. It follows from work of Mayordomo [May94] that the consequent hol...
متن کاملAmplitude metrics for field retrieval with hard-edged and uniformly illuminated apertures.
In field retrieval, the amplitude and phase of the generalized pupil function for an optical system are estimated from multiple defocused measurements of the system point-spread function. A baseline field reconstruction algorithm optimizing a data consistency metric is described. Additionally, two metrics specifically designed to incorporate a priori knowledge about pupil amplitude for hard-edg...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 2003
ISSN: 0304-3975
DOI: 10.1016/s0304-3975(02)00810-1