OWLlink Extension:

Working Draft October 2008

This version:
Latest version:
Thorsten Liebig, Ulm University
Olaf Noppens, Ulm University
Marko Luther, DOCOMO Euro-Labs Munich


OWLlink provides a declarative interface for – among other things – asserting OWL axioms to a Knowledge Base (KB) of an OWL reasoner. This OWLlink extension adds the ability to retract previously asserted axioms from KBs.

Status of this Document

May Be Superseded

This version of the OWLlink structural specification refers to the public OWL 2 working draft as of April 11th 2008 (http://www.w3.org/TR/2008/WD-owl2-syntax-20080411/) and will soon be superseded by an updated specification in order to align with the latest OWL 2 working draft or recommendation.

Please Comment

The OWLlink Working Group seeks public feedback on these Working Drafts. Please send your comments to public-comments@owllink.org or post to the public discussion forum at http://www.owllink.org/forum/.

This extension is being published as one of a set of 2 documents:

  1. Retraction Structural Specification (this document)
  2. Retraction HTTP/XML Binding

1 Introduction

The OWLlink core interface [OWLlink Structural Specification] relies on a certain kind of incremental batch-oriented reasoning procedure. After submission of a set of axioms a client can pose some queries, add further axioms, query again, and so on. Deletion of axioms is ony possible by releasing a KB and re-submission of axioms. This document describes the retraction extension of OWLlink which allows to retract previously told KB fragments on axiom level.

This extension is based on the same preliminaries than the OWLlink core. It therefore uses the same notational conventions of OWL 2 [OWL 2 Syntax] [OWL 2 Semantics] such as UML for structural specification of language primitives.

2 Retraction

The Retract request is the inverse command to Tell and takes a set of OWL axioms and removes them from the given KB specified by its URI as shown in Figure 1. The removal must be sensitive to the rules of structural equivalence of OWL 2. That is, an axiom can only be removed from a KB if and only if the KB contains an axiom which is structural equivalent to the one given in the retraction request. A server must not respond with an error if a KB does not contain a structurally equivalent axiom but is free to provide a warning. If all axioms of a retraction request are successfully removed from the KB, the server should respond with a OK response.

Retraction Request
Figure 1. Retraction Request (the Tell request is rendered semi-transparently to show the symmetry)

3 References

[OWLlink Structural Specification]
OWLlink: Structural Specification. Sean Bechhofer, Thorsten Liebig, Marko Luther, Olaf Noppens. Working Draft, October 2008. http://www.owllink.org/owllink-20081001/
[OWL 2 Syntax]
OWL 2 Web Ontology Language: Structural Specification and Functional-Style Syntax Boris Motik, Peter F. Patel-Schneider, Ian Horrocks. W3C Working Draft, 11 April 2008, http://www.w3.org/TR/2008/WD-owl2-syntax-20080411/
[OWL 2 Semantics]
OWL 2 Web Ontology Language: Model-Theoretic Semantics Bernardo Cuenca Grau, Boris Motik. W3C Working Draft, 11 April 2008, http://www.w3.org/TR/2008/WD-owl2-semantics-20080411/