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Well-Founded Semantics for Boolean Grammars

  • Vassilis Kountouriotis
  • Christos Nomikos
  • Panos Rondogiannis
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4036)

Abstract

Boolean grammars [A. Okhotin, Information and Computation 194 (2004) 19-48] are a promising extension of context-free grammars that supports conjunction and negation. In this paper we give a novel semantics for boolean grammars which applies to all such grammars, independently of their syntax. The key idea of our proposal comes from the area of negation in logic programming, and in particular from the so-called well-founded semantics which is widely accepted in this area to be the “correct” approach to negation. We show that for every boolean grammar there exists a distinguished (three-valued) language which is a model of the grammar and at the same time the least fixed point of an operator associated with the grammar. Every boolean grammar can be transformed into an equivalent (under the new semantics) grammar in normal form. Based on this normal form, we propose an \({\mathcal{O}(n^3)}\) algorithm for parsing that applies to any such normalized boolean grammar. In summary, the main contribution of this paper is to provide a semantics which applies to all boolean grammars while at the same time retaining the complexity of parsing associated with this type of grammars.

Keywords

Normal Form Logic Program Logic Programming Terminal Symbol Free Version 
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 2006

Authors and Affiliations

  • Vassilis Kountouriotis
    • 1
  • Christos Nomikos
    • 2
  • Panos Rondogiannis
    • 1
  1. 1.Department of Informatics & TelecommunicationsUniversity of AthensAthensGreece
  2. 2.Department of Computer ScienceUniversity of IoanninaIoanninaGreece

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