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Normal forms and the complexity of computations of logic programs

  • Vít Ochozka
  • Olga Štěpánková
  • Petr Štěpánek
  • Jan Hric
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 385)

Abstract

It is shown that every pure logic program can be transformed to a normal form without changing the lengths of computations and the data flow during computation. The lengths of computations of logic programs in normal form are studied. Some sufficient conditions on the syntactic structure of programs are formulated that imply that the length of computation is linear with respect to the length of the input. On the other hand, it is shown that logic programs with the simplest possible normal forms, i.e. programs with at most one called node and one calling leaf, can simulate computations of arbitrary Turing machine. Consequently, such programs can exhibit arbitrary complex computational behaviour.

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References

  1. A.K. Chandra and D. Harel, Horn Clause Queries and Generalizations J.Logic Programming 2 (1985), 1–15CrossRefGoogle Scholar
  2. Y.Moschovakis, Elementary Induction on Abstract Structures, Studies in Logic Vol. 77, North Holland, 1974Google Scholar
  3. E.Y Shapiro Alternation and the Computational Complexity of Logic Programs, J. Logic Pragramming 1(1984), 19–33CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1989

Authors and Affiliations

  • Vít Ochozka
  • Olga Štěpánková
  • Petr Štěpánek
    • 1
  • Jan Hric
  1. 1.Department of Computer ScienceCharles UniversityPraha 1Czechoslovakia

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