Implementing OWL Defaults

While it has been argued that knowledge representation for the World Wide Web must respect the open world assumption due to the “open” nature of the Web, users of the Web Ontology Language (OWL) have often requested some form of non-monotonic reasoning. In this paper, we present preliminary optimizations and an implementation of a restricted version of Reiter’s default logic as an extension to the description logic fragment of OWL, OWL DL. We implement the decision procedure for this logic in the OWL DL reasoner Pellet, and exploit its support for incremental reasoning through update to improve performance. We also extend an open source ontology editor SWOOP with default rules editing support.