One-unambiguous regular languages
Information and Computation
On testing satisfiability of tree pattern queries
VLDB '04 Proceedings of the Thirtieth international conference on Very large data bases - Volume 30
XPath satisfiability in the presence of DTDs
Journal of the ACM (JACM)
Satisfiability of downward XPath with data equality tests
Proceedings of the twenty-eighth ACM SIGMOD-SIGACT-SIGART symposium on Principles of database systems
Satisfiability of simple xpath fragments in the presence of dtds
Proceedings of the eleventh international workshop on Web information and data management
Extending the tractability results on XPath satisfiability with sibling axes
XSym'10 Proceedings of the 7th international XML database conference on Database and XML technologies
Satisfiability of XPath queries with sibling axes
DBPL'05 Proceedings of the 10th international conference on Database Programming Languages
XPath query satisfiability is in PTIME for real-world DTDs
XSym'07 Proceedings of the 5th international conference on Database and XML Technologies
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The XPath satisfiability problem is to decide, for an XPath expression q and a DTD D, if there exists an XML document t valid against D such that the answer of q on t is nonempty. It is shown that the satisfiability problem is intractable for many XPath fragments. In this paper, we focus on fixed DTDs and consider the problem under fixed DTDs. We first show that, for a very restricted XPath fragment, the satisfiability problem is NP-complete under fixed DTDs. Then we show several XPath fragments for which satisfiability is in PTIME under fixed DTDs.