Structural Properties of XPath Fragments

  • Michael Benedikt
  • Wenfei Fan
  • Gabriel M. Kuper
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2572)


We study structural properties of each of the main sublanguages of XPath [8] commonly used in practice. First, we characterize the expressive power of these language fragments in terms of both logics and tree patterns. Second, we investigate closure properties, focusing on the ability to perform basic Boolean operations while remaining within the fragment. We give a complete picture of the closure properties of these fragments, treating XPath expressions both as functions of arbitrary nodes in a document tree, and as functions that are applied only at the root of the tree. Finally, we provide sound and complete axiom systems and normal forms for several of these fragments. These results are useful for simplification of XPath expressions and optimization of XML queries.


Normal Form Tree Pattern Expressive Power Axiom System Closure Property 
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 2003

Authors and Affiliations

  • Michael Benedikt
    • 1
  • Wenfei Fan
    • 1
  • Gabriel M. Kuper
    • 2
  1. 1.Bell LaboratoriesMurray HillUSA
  2. 2.Università di TrentoTrentoItaly

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