ExpTime Reasoning for Contextualized ALC

The combination of often heterogeneous and contradicting knowledge sources in the Semantic Web demands for methods to represent and reason with a notion of context. Among context representation frameworks, Contextualized Knowledge Repository (CKR) is a novel proposal grounded in the well-studied AI theories of context and aims at bringing the advantages of contextual representation to the Semantic Web. In this paper we show that reasoning in ALC-based CKR is decidable and EXPTIME-complete. The result is presented trough a reduction from ALC-based CKRs to ALCO(t) knowledge bases. This result is important, because it shows that the addition of the contextual layer does not come at the cost of increased complexity of reasoning