Data on the Web: from relations to semistructured data and XML
Data on the Web: from relations to semistructured data and XML
Index Structures for Path Expressions
ICDT '99 Proceedings of the 7th International Conference on Database Theory
XPath Containment in the Presence of Disjunction, DTDs, and Variables
ICDT '03 Proceedings of the 9th International Conference on Database Theory
UnQL: a query language and algebra for semistructured data based on structural recursion
The VLDB Journal — The International Journal on Very Large Data Bases
Containment and equivalence for a fragment of XPath
Journal of the ACM (JACM)
Expressiveness and complexity of XML Schema
ACM Transactions on Database Systems (TODS)
XPath satisfiability in the presence of DTDs
Journal of the ACM (JACM)
Finite Automata, Digraph Connectivity, and Regular Expression Size
ICALP '08 Proceedings of the 35th international colloquium on Automata, Languages and Programming, Part II
The complexity of query containment in expressive fragments of XPath 2.0
Journal of the ACM (JACM)
Satisfiability and containment problem of structural recursions with conditions
ADBIS'10 Proceedings of the 14th east European conference on Advances in databases and information systems
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In this paper we introduce named expressions, with which a name can be assigned to an XPath expression, and then this name can be used wherever a location step may occur. Named expressions may contain other named expressions or themselves, which gives rise to a new kind of recursivity different from the recursivity already involved in axis descendant, ancestor etc. The idea was inspired by the possibility of defining functions in XQuery, which may call other user-defined functions in their body. Named expressions can be regarded as a simplified version of user-defined functions in the context of XPath. We only consider downward axis with and without negations. We clarify the relationship between the different types of recursions, including transitive closure, and we also establish complexity results for the satisfiability and containment problem for different fragments of this enhanced XPath language. These results are based on the results of the static analysis of structural recursions [11,10].