Structural Properties of XPath Fragments

Michael Benedikt, Wenfei Fan, Gabriel M. Kuper

Research output: Chapter in Book/Report/Conference proceedingConference contribution


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.
Original languageEnglish
Title of host publicationDatabase Theory - ICDT 2003
Subtitle of host publication9th International Conference, Siena, Italy, January 8-10, 2003, Proceedings
PublisherSpringer Berlin Heidelberg
Number of pages17
ISBN (Electronic)978-3-540-36285-2
ISBN (Print)978-3-540-00323-6
Publication statusPublished - 2003


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