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Author Benedikt, Michael ♦ Fan, Wenfei ♦ Geerts, Floris
Source ACM Digital Library
Content type Text
Publisher Association for Computing Machinery (ACM)
File Format PDF
Copyright Year ©2008
Language English
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Subject Keyword Containment ♦ DTDs ♦ Satisfiability ♦ XML ♦ XPath
Abstract We study the satisfiability problem associated with XPath in the presence of DTDs. This is the problem of determining, given a query $\textit{p}$ in an XPath fragment and a DTD $\textit{D},$ whether or not there exists an XML document $\textit{T}$ such that $\textit{T}$ conforms to $\textit{D}$ and the answer of $\textit{p}$ on $\textit{T}$ is nonempty. We consider a variety of XPath fragments widely used in practice, and investigate the impact of different XPath operators on the 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. Furthermore, 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. Finally, we investigate the problem for XPath fragments with sibling axes, exploring the impact of horizontal modalities on the satisfiability analysis.
ISSN 00045411
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2008-05-01
Publisher Place New York
e-ISSN 1557735X
Journal Journal of the ACM (JACM)
Volume Number 55
Issue Number 2
Page Count 79
Starting Page 1
Ending Page 79


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Source: ACM Digital Library