Abstract: In an open, constantly changing and collaborative environment like the forthcoming Semantic Web, it is reasonable to expect that knowledge sources will contain noise and inaccuracies. It is well known,as the logical foundation of the Semantic Web, description logic is lack of the ability of tolerating inconsistent or incomplete data. Recently, some paraconsistent scenarios were used to avoid trivial inferences so that inconsistencies occurring in ontologics could be tolerated. Their inference powers are always weaker than that of classical description logics even handling consistent ontologoies since they cost the inference power of description logics. hhis paper proposed a tableau algorithm based on sign transformation which has stronger reasoning ability. We proved that the new paraconsistent tableau algorithm is decidable and has the same reasoning ability with the classical Description Logic over consistent ontologies.

Key words: Semantic Web,Description logic ALC,hableau,Paraconsistent tableau,Inconsistency handling