Most semantic annotation approaches create mappings between the documents and the
ontologies (i.e. typically an annotated term or document becomes an instance of an
ontology) (Reeve & Han, 2005; Uren et al., 2006). This can be an ideal solution when
retrieving documents. However, from a maintenance perspective this approach becomes
increasingly difficult to apply with billions of documents that are mapped to millions of
concepts in various ontologies (Kiryakov et al., 2004; Uren et al., 2006). Reasoning