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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/956

Title: XPath satisfiability in the presence of DTDs
Authors: Benedikt, M.
Fan, W.
GEERTS, Floris
Issue Date: 2005
Publisher: ACM
Citation: Proceedings of the twenty-fourth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems. p. 25-36.
Abstract: We study the satisfiability problem associated with XPath in the presence of DTDs. This is the problem of determining, given a query p in an XPath fragment and a DTD D, whether or not there exists an XML document T such that T conforms to D and the answer of p on T is nonempty. We consider a variety of XPath fragments widely used in practice, and investigate the impact of different XPath operators on satisfiability analysis. We first study the problem for negation-free XPath fragments with and without upward axes, recursion and data-value joins, identifying which factors lead to tractability and which to NP-completeness. We then turn to fragments with negation but without data values, establishing lower and upper bounds in the absence and in the presence of upward modalities and recursion. We show that with negation the complexity ranges from PSPACE to EXPTIME. Moreover, when both data values and negation are in place, we find that the complexity ranges from NEXPTIME to undecidable. Finally, we give a finer analysis of the problem for particular classes of DTDs, exploring the impact of various DTD constructs, identifying tractable cases, as well as providing the complexity in the query size alone.
URI: http://hdl.handle.net/1942/956
Link to publication: http://doi.acm.org/10.1145/1065167.1065172
ISBN: 1-59593-062-0
Category: C1
Type: Proceedings Paper
Appears in Collections: Databases and Theoretical Computer Science

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