XPath with Conditional Axis Relations

  • Maarten Marx
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 2992)


This paper is about the W3C standard node-addressing language for XML documents, called XPath. XPath is still under development. Version 2.0 appeared in 2001 while the theoretical foundations of Version 1.0 (dating from 1998) are still being widely studied. The paper aims at bringing XPath to a “stable fixed point” in its development: a version which is expressively complete, still manageable computationally, with a user-friendly syntax and a natural semantics. We focus on an important axis relation which is not expressible in XPath 1.0 and is very useful in practice: the conditional axis. With it we can express paths specified by for instance “do a child step, while test is true at the resulting node”. We study the effect of adding conditional axis relations to XPath on its expressive power and the complexity of the query evaluation and query equivalence problems. We define an XPath dialect \(\mathcal{X}\)CPath which is expressively complete, has a linear time query evaluation algorithm and for which query equivalence given a DTD can be decided in exponential time.


Model Check Transitive Closure Expressive Power Query Evaluation Consequence Problem 
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 2004

Authors and Affiliations

  • Maarten Marx
    • 1
  1. 1.Language and Inference Technology, ILLCUniversiteit van AmsterdamThe Netherlands

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