Integrating Ontologies And Rules: An Overview With Focus On SWRL.pdf

This chapter explores the integration of Web Ontology Language OWL (based on Description Logics and open-world assumption) with rule-based systems (using logic programming). Challenges arise due to contrasting paradigms: OWL's open-world vs. rules' closed-world assumptions.

Key Concepts:

OWL DL: Recommended W3C language for expressing ontologies on the Semantic Web, based on first-order predicate logic.
Rule-based systems (logic programming): Use rule-like expressions to infer conclusions from premises, often employed in industrial applications.
SWRL (Semantic Web Rule Language): Unrestricted union of OWL DL and binary Horn logic, allowing for expressive rules while retaining decidability through "DL-Safe" restriction limiting variable values to named individuals.
DL-Safe Rules: SWRL rules that adhere to the DL-Safety condition, ensuring decidability and enabling practical implementations like KAON2.

Approaches:

The chapter discusses various hybrid approaches:

SWRL: Combines OWL DL with Horn logic, offering powerful rule modeling but undecidability without DL-Safe restriction.
Rule Fragments of OWL DL:
DLP (Naive Horn Fragment): Simplest fragment allowing basic rule forms.
Horn-SHIQ: More sophisticated fragment encompassing DLP.
* Hybrid Systems: Combine OWL with existing rule languages, blending open and closed-world assumptions.

Significance:

The integration of OWL and rules is crucial for building comprehensive and flexible ontologies capable of reasoning under uncertainty while leveraging the strengths of both paradigms. SWRL and DL-Safe Rules represent promising directions in this area.