This survey gives an overview of formal results on the XML query language XPath. We
identify several important fragments of XPath, focusing on subsets of XPath 1.0. We then …

Labeled unranked trees are used as a model of XML documents, and logical languages for
them have been studied actively over the past several years. Such logics have different …

Our experimental analysis of several popular XPath processors reveals a striking fact: Query
evaluation in each of the systems requires time exponential in the size of queries in the …

Research on information extraction from Web pages (wrap**) has seen much activity
recently (particularly systems implementations), but little work has been done on formally …

XPath is a simple language for navigating an XML tree and returning a set of answer nodes.
The focus in this paper is on the complexity of the containment problem for various …

A number of techniques have been developed to facilitate powerful data retrieval on the
Web and Semantic Web. Three categories of Web query languages can be distinguished …

XPath 1.0 is a variable free language designed to specify paths between nodes in XML
documents. Such paths can alternatively be specified in first-order logic. The logical …

We study the complexity and expressive power of conjunctive queries over unranked
labeled trees represented using a variety of structure relations such as “child”,“descendant” …

We give semantic characterizations of the expressive power of navigational XPath (aka Core
XPath) in terms of first order logic. XPath can be used to specify sets of nodes and sets of …

This paper is about the W3C standard node-addressing language for XML documents,
called XPath. XPath is still under development. Version 2.0 appeared in 2001 while the …