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Combining XML querying with ontology reasoning: Xcerpt and DIG
Linköping University, Department of Computer and Information Science, TCSLAB. Linköping University, The Institute of Technology.
Linköping University, Department of Computer and Information Science, TCSLAB. Linköping University, The Institute of Technology.
2006 (English)In: Online Proceedings of RuleMLWorkshop: Ontology and Rule Integration, Athens, Georgia, USA, 2006Conference paper (Refereed)
Abstract [en]

The paper addresses the problem of combining ontological

reasoning with querying XML data. We present an extension

of a rule-based XML query and transformation language

Xcerpt. The extension allows to interface an ontology

reasoner from Xcerpt programs. In this way querying can

employ the ontology information, for instance to filter out

semantically irrelevant answers. Communication between

Xcerpt programs and ontology reasoner is based on DIG

interface. The extension can be implemented without modifying

the underlying Xcerpt implementation.


Place, publisher, year, edition, pages
National Category
Engineering and Technology
URN: urn:nbn:se:liu:diva-12917OAI: diva2:17391
Available from: 2008-01-29 Created: 2008-01-29
In thesis
1. Types for XML with Application to Xcerpt
Open this publication in new window or tab >>Types for XML with Application to Xcerpt
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

XML data is often accompanied by type information, usually expressed by some schema language. Sometimes XML data can be related to ontologies defining classes of objects, such classes can also be interpreted as types. Type systems proved to be extremely useful in programming languages, for instance to automatically discover certain kinds of errors. This thesis deals with an XML query language Xcerpt, which originally has no underlying type system nor any provision for taking advantage of existing type information. We provide a type system for Xcerpt; it makes possible type inference and checking type correctness.

The system is descriptive: the types associated with Xcerpt constructs are sets of data terms and approximate the semantics of the constructs. A formalism of Type Definitions is adapted to specify such sets. The formalism may be seen as a simplification and abstraction of XML schema languages. The type inference method, which is the core of this work, may be seen as abstract interpretation. A non standard way of assuring termination of fixed point computations is proposed, as standard approaches are too inefficient. The method is proved correct wrt. the formal semantics of Xcerpt.

We also present a method for type checking of programs. A success of type checking implies that the program is correct wrt. its type specification. This means that the program produces results of the specified type whenever it is applied to data of the given type. On the other hand, a failure of type checking suggests that the program may be incorrect. Under certain conditions (on the program and on the type specification), the program is actually incorrect whenever the proof attempt fails.

A prototype implementation of the type system has been developed and usefulness of the approach is illustrated on example programs.

In addition, the thesis outlines possibility of employing semantic types (ontologies) in Xcerpt. Introducing ontology classes into Type Definitions makes possible discovering some errors related to the semantics of data queried by Xcerpt. We also extend Xcerpt with a mechanism of combining XML queries with ontology queries. The approach employs an existing Xcerpt engine and an ontology reasoner; no modifications are required.

Place, publisher, year, edition, pages
Institutionen för datavetenskap, 2008. 175 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1156
XML, types, Xcerpt, XML schema, ontologies, XML querying
National Category
Computer Science
urn:nbn:se:liu:diva-10687 (URN)978-91-85895-08-3 (ISBN)
Public defence
2008-02-19, Visionen, Hus B, Campus Valla, Linköpings universitet, Linköping, 13:15 (English)
Available from: 2008-01-29 Created: 2008-01-29 Last updated: 2015-03-13

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