ABSTRACT
In this work we investigate the satisfiability problem for the logic XPath(↓*, ↓,=), that includes all downward axes as well as equality and inequality tests. We address this problem in the absence of DTDs and the sibling axis. We prove that this fragment is decidable, and we nail down its complexity, showing the problem to be ExpTime-complete. The result also holds when path expressions allow closure under the Kleene star operator. To obtain these results, we introduce a new automaton model over data trees that captures XPath(↓*, ↓,=) and has an ExpTime emptiness problem. Furthermore, we give the exact complexity of several downward-looking fragments.
- M. Benedikt, W. Fan, and F. Geerts. XPath satisfiability in the presence of DTDs. J.ACM, 55(2), 2008. Google Scholar
Digital Library
- M. Bojanczyk, C. David, A. Muscholl, T. Schwentick, and L. Segoufin. Two-variable logic on data trees and XML reasoning. In PODS, pages 10--19. ACM, 2006. Google Scholar
Digital Library
- B. S. Chlebus. Domino-tiling games. J. Comput. Syst. Sci., 32(3):374--392, 1986. Google Scholar
Digital Library
- J. Clark and S. DeRose. XML path language (XPath). Website, November 1999. W3C Recommendation. http://www.w3.org/TR/xpath.Google Scholar
- F. Geerts and W. Fan. Satisfiability of XPath queries with sibling axes. In DBPL, volume 3774, pages 122--137. Springer, 2005. Google Scholar
Digital Library
- G. Gottlob, C. Koch, and R. Pichler. Efficient algorithms for processing XPath queries. ACM Trans. Database Syst., 30(2):444--491, 2005. Google Scholar
Digital Library
- M. Jurdzinski and R. Lazić. Alternating automata on data trees and XPath satisfiability. CoRR, abs/0805.0330, 2008.Google Scholar
- M. Marx. First order paths in ordered trees. In ICDT, volume 3363, pages 114--128. Springer, 2005. Google Scholar
Digital Library
- B. ten Cate. The expressivity of XPath with transitive closure. In PODS, pages 328--337. ACM Press, 2006. Google Scholar
Digital Library
- B. ten Cate and L. Segoufin. XPath, transitive closure logic, and nested tree walking automata. In PODS, pages 251--260. ACM Press, 2008. Google Scholar
Digital Library
Index Terms
Satisfiability of downward XPath with data equality tests
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