Can OWL and Logic Programming Live Together Happily Ever After?

A paper written by Ulrike Sattler, Boris Motik, Riccardo Rosati and Ian Horrocks. It was presented at the ISWC2006.

[edit] Abstract

Logic programming (LP) is often seen as a way to overcome several shortcomings of the Web Ontology Language (OWL), such as the inability to model integrity constraints or perform closed-world querying. However, the open-world semantics of OWL seems to be fundamentally incompatible with the closed-world semantics of LP. This has sparked a heated debate in the Semantic Web community, resulting in proposals for alternative ontology languages based entirely on logic programming. To help resolving this debate, we investigate the practical use cases which seem to be addressed by logic programming. In fact, many of these requirements have already been addressed outside of the Semantic Web. By drawing inspiration from these existing formalisms, we present a novel logic of hybrid MKNF knowledge bases, which seamlessly integrates OWL with LP. We are thus capable of addressing the identified use cases without a radical change in the architecture of the Semantic Web.

The schedule for this talk can be found in the conference programme and a linked list of all talks is provided in the article on ISWC2006 papers. This article has originally been created from the RDF metadata for ISWC 2006.

[edit] Questions

The following questions have been asked after the talk at ISWC2006.

• "Don't our conclusions change if we learn about named individuals, such as Jesus' mother?"

• "So what is the problem?"

• "Do you want everybody's mother to be required to be known?"

• "No, you can have named and 'unnamed' individuals."

• "How can you deal the nondeterminism? Isn't it very complex (PSpace)?"

• "We have investigated data complexity and looked at DLs that have P or co-NP data complexity. In the case of co-NP the reasoning is <math>\Sigma^P_2</math> hard, i.e. 2nd level of polynomial hierarchy."
• "We also considered weaker logics without negation in the head. This also helped to simplify the complexity. The paper and accompanying technical report give further explanations."