Dear all, for those of you who are interested in decidability questions in the context of ontology languages, let me recommend a few readings:
For a general introduction and definition of the concept of decidability, there are many textbooks which can be consulted, e.g. Barwise, J.; Etchemendy, J.: Language, Proof, and Logic. CSLI Publications, New York: Seven-Bridges-Press, 2000 or lexicon articles like that in the Stanford Encyclopedia of Philosophy on "Automatic Theorem Proving" (section 3): http://plato.stanford.edu/entries/reasoning-automated/ W.r.t. to RDF/S and OWL-DL (description logics) in particular, the following paper is helpful: Ian Horrocks, Peter F. Patel-Schneider: Three Theses of Representation in the Semantic Web. Proceedings of WWW2003, May 20-24, 2003, Budapest, Hungary, 39--47 Some more background information can be found in: Peter F. Patel-Schneider: Building the Semantic Web Tower from RDF Straw. Nineteenth International Joint Conference on Artificial Intelligence. Edinburgh, Scotland, August 2005. (This paper shows that - and how - paradoxes can be formulated in full RDF/S) Peter Patel-Schneider, Jerome Simeon: The Yin/Yang Web: XML Syntax and RDF Semantics. The Eleventh International World Wide Web Conference. Honolulu, Hawaii, May 2002. Jeff Z. Pan and Ian Horrocks: RDFS(FA): A DL-ised Sub-language of RDFS. Proc. of the 2003 Description Logic Workshop (DL 2003), Vol. 81 of CEUR Proceedings, Sunsite Aachen. All of these papers can be retrieved from the Web. Finally, I would like to give a reading recommendation for those who are interested in a methodological and constructive approach to predication, concept formation, truth and verification, reasoning and the construction of scientific theories. It is a textbook on the freshman level (at least as it used to be before our universities were punished with the introduction of the Bachelor system...): W. Kamlah, P. Lorenzen: Logical Propaedeutic. Pre-School of Reasonable Discourse. Lanham etc.: University Press of America, 1984 Hope this helps, Best, -- Guenther
