XPath is a W3C standard that plays a crucial role in several in uential query, transformation, and schema standards for XML. Motivated by the larger challenge of XML query optimization, we investigate the problem of containment of XPath expressions under integrity constraints that are in turn formulated with the help of XPath expressions. Our core formalism consists of a fragment of XPath that ...

XML languages, such as XQuery, XSLT and SQL/XML, employ XPath as the search and extraction language. XPath expressions often define complicated navigation, resulting in expensive query processing, especially when executed over large collections of documents. In this paper, we propose a framework for exploiting materialized XPath views to expedite processing of XML queries. We explore a class of...

Several web applications (such as processing RSS feeds or web service messages) rely on XPath-based data manipulation tools. Web developers need to use XPath queries effectively on increasingly larger web collections containing hundreds of thousands of XML documents. Even when tasks only need to deal with a single document at a time, developers benefit from understanding the behaviour of XPath ...

Contemporary XPath query engines evaluate queries in time exponential in the sizes of input queries, a fact that has gone unnoticed for a long time. Recently, the first mainmemory evaluation algorithm for XPath 1.0 with polynomial time combined complexity, i.e., which runs in polynomial time both with respect to the size of the data and the queries, has been published (cf. [11]). In this paper,...

Some recent research works face the challenge to map XML documents to RDF triples. Ontologies are used to establish semantic connections among XML applications, and some mechanisms have been defined to query them with natural XML query languages like XPath and XML Query. Generally structure-mapping approaches define a simple translation between trivial XPath expressions and a target RDF query l...

XPath is the standard language for navigating XML documents and returning a set of matching nodes. We present a sound and complete decision procedure for containment of XPath queries as well as other related XPath decision problems such as satisfiability, equivalence, overlap and coverage. The considered XPath fragment covers most of the language features used in practice. Specifically, we prop...

As a query language for navigating XML trees and selecting a set of element nodes, XPath is ubiquitous in XML applications. One important issue of XPath queries is containment checking, which is known as a co-NP complete. The homomorphism relationship between two XPath trees, which is a PTIME problem, is a sufficient but not necessary condition for the containment relationship. We propose a new...

The location path language XPath is of particular importance for XML applications since it is a core component of many XML processing standards such as XSLT or XQuery. In this paper, based on axis symmetry of XPath, equivalences of XPath 1.0 location paths involving reverse axes, such as ancestor and preceding, are established. These equivalences are used as rewriting rules in an algorithm for ...

Bisherige XML-Datenbanken erlauben lediglich eine eingeschränkte Unterstützung von zeitlichen Daten und Anfragen. Das hier vorgestellte zeitliche Modell T-XPath erweitert das bisherige Datenmodell und die Anfragesprache XPath um eine flexible und effiziente Modellierung, Verwaltung und Abfragemöglichkeit von zeitlichen Informationen. Als Grundlage dienen abstrakte zeitliche Datentypen (ADT), di...

Whenever XML data is distributed over several web sites but follows a global schema defined by a DTD, i.e. multiple sites contain fragments of a global ‘virtual’ XML document, and the accessible XML content stored on a site can be described by an XPath expression, it may be considerably advantageous to search for XML data only on those sites which contain a relevant fragment of the distributed ...