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On the time and tape complexity of hyper(1)-AFL's

  • Wilhelm J. Erni
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 52)

Abstract

It is well known that the membership question for the smallest hyper-AFL is NP-complete. One may ask whether this is the case for the smallest hyper(1)-AFL, too. Thus we study the family of block-indexed languages. We show that this family is a hyper(1)-AFL which is not a hyper-AFL and that it is contained in the family of languages log(n)-tape reducible to the context-free languages. This implies that the family of block-indexed languages, together with the smallest hyper(1)-AFL, has a tractable membership question and tape complexity log2(n). Finally we note that the set {ww / wε {a, b}*} is not a block-indexed language.

Keywords

Input Word Dead State Finite Control Input Head Leftmost Derivation 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1977

Authors and Affiliations

  • Wilhelm J. Erni
    • 1
    • 2
  1. 1.Inst. f. Angew. InformatikUniversität KarlsruheKarlsruheFed. Rep. Germany
  2. 2.Inst. f. Angew. MathematikUniversität HeidelbergHeidelbergFed. Rep. Germany

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