An NL hierarchy

Jianer Chen, Jim Cox, Bud Mishra

Research output: Contribution to journalArticle

Abstract

We introduce a new nondeterministic oracle model. Our model is significantly different from all previous space-bounded oracle models, and has the following properties: First, it permits a nontrivial NL-hierarchy, which does not collapse without a similar consequence for the polynomial-time hierarchy. This is immediate from the result that ∑ k p is exactly the 2kth level in our NL-hierarchy, for all k≥1. On the other hand, it still behaves very well in relativised worlds. In particular, the new model satisfies the Immerman-Szelepcsenyi theorem and Savitch's theorem in the relativized worlds for oracle sets in each level of the polynomial-time hierarchy.

Original languageEnglish (US)
Pages (from-to)21-26
Number of pages6
JournalInformation Processing Letters
Volume39
Issue number1
DOIs
StatePublished - Jul 12 1991

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Polynomial time
Polynomials
Theorem
Model
Hierarchy

Keywords

  • Computational complexity
  • nondeterministic computation
  • query machines
  • space-bounded computation

ASJC Scopus subject areas

  • Computational Theory and Mathematics

Cite this

An NL hierarchy. / Chen, Jianer; Cox, Jim; Mishra, Bud.

In: Information Processing Letters, Vol. 39, No. 1, 12.07.1991, p. 21-26.

Research output: Contribution to journalArticle

Chen, Jianer ; Cox, Jim ; Mishra, Bud. / An NL hierarchy. In: Information Processing Letters. 1991 ; Vol. 39, No. 1. pp. 21-26.
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