A Variant of Earley Deduction with Partial Evaluation

  • Stefan Brass
  • Heike Stephan
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7994)


We present an algorithm for query evaluation given a logic program consisting of function-free Datalog rules. The algorithm is based on Earley Deduction [7,10], but uses explicit states to eliminate rules which are no longer needed, and partial evaluation to minimize the work at runtime. At least in certain cases, the new method is more efficient than our SLDMagic-method [2], and also beats the standard Magic set method. It is also theoretically interesting, because it consumes one EDB fact in each step. Because of its origin, it is especially well suited for parsing applications, e.g. for extracting data from web pages. However, it has the potential to speed up basic Datalog reasoning for many semantic web applications.


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© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Stefan Brass
    • 1
  • Heike Stephan
    • 1
  1. 1.Institut für InformatikMartin-Luther-Universität Halle-WittenbergHalle (Saale)Germany

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