Satisfiability of Simple XPath Fragments under Duplicate-Free DTDs
| Autor: | Yuji Fukushima, Nobutaka Suzuki, Kosetsu Ikeda |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: |
Computer science
computer.internet_protocol InformationSystems_DATABASEMANAGEMENT Empty set Expression (computer science) Satisfiability Combinatorics TheoryofComputation_MATHEMATICALLOGICANDFORMALLANGUAGES Artificial Intelligence Hardware and Architecture Simple (abstract algebra) Path (graph theory) ComputingMethodologies_DOCUMENTANDTEXTPROCESSING Computer Vision and Pattern Recognition Electrical and Electronic Engineering Algorithm computer Software XML XPath |
| Zdroj: | IEICE transactions on information and systems. (5):1029-1042 |
| ISSN: | 0916-8532 |
| Popis: | In this paper, we consider the XPath satisfiability problem under restricted DTDs called “duplicate free”. For an XPath expression q and a DTD D, q is satisfiable under D if there exists an XML document t such that t is valid against D and that the answer of q on t is nonempty. Evaluating an unsatisfiable XPath expression is meaningless, since such an expression can always be replaced by an empty set without evaluating it. However, it is shown that the XPath satisfiability problem is intractable for a large number of XPath fragments. In this paper, we consider simple XPath fragments under two restrictions: (i) only a label can be specified as a node test and (ii) operators such as qualifier ([ ]) and path union (∪) are not allowed. We first show that, for some small XPath fragments under the above restrictions, the satisfiability problem is NP-complete under DTDs without any restriction. Then we show that there exist XPath fragments, containing the above small fragments, for which the satisfiability problem is in PTIME under duplicate-free DTDs. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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