Guarded Hybrid Knowledge Bases

TL;DR

This paper introduces guarded hybrid knowledge bases combining Description Logics and guarded logic programs, demonstrating their decidability and complexity, and comparing them to existing DL+log approaches.

Contribution

It defines guarded hybrid knowledge bases, proves their satisfiability is decidable for DLRO, and analyzes their computational complexity and advantages over prior methods.

Findings

Decidability of satisfiability for g-hybrid knowledge bases with DLRO

Satisfiability checking is 2-EXPTIME-complete

Discussion of advantages and disadvantages compared to DL+log

Abstract

Recently, there has been a lot of interest in the integration of Description Logics and rules on the Semantic Web.We define guarded hybrid knowledge bases (or g-hybrid knowledge bases) as knowledge bases that consist of a Description Logic knowledge base and a guarded logic program, similar to the DL+log knowledge bases from (Rosati 2006). G-hybrid knowledge bases enable an integration of Description Logics and Logic Programming where, unlike in other approaches, variables in the rules of a guarded program do not need to appear in positive non-DL atoms of the body, i.e. DL atoms can act as guards as well. Decidability of satisfiability checking of g-hybrid knowledge bases is shown for the particular DL DLRO, which is close to OWL DL, by a reduction to guarded programs under the open answer set semantics. Moreover, we show 2-EXPTIME-completeness for satisfiability checking of such g-hybrid knowledge bases. Finally, we discuss advantages and disadvantages of our approach compared with DL+log knowledge bases.