Notions of indistinguishability for Semantic Web languages

The paper reviews the notions of expressiveness of description logics from (N. Kurtonina and M. de Rijke. Expressiveness of concept expressions in first-order description logics. Artificial Intelligence, 107:303-333, 1999) and exemplifies their use in the development in Semantic Web languages. The notion of bisimulation-which characterizes the description logic ACC-provides a direct link to what's in the field of sociology called social network analysis. The perspective on data in this field-data are represented as labeled graphs-fits exactly the modeling intuitions of web languages like OIL and DAML+OIL. This is exemplified in the study of trophic networks. A further connection is established between web languages and hybrid logic, and an extension of OIL with a limited form of self reference is proposed.