- From: Dieter Fensel <dieter@cs.vu.nl>
- Date: Thu, 13 Apr 2000 00:53:29 +0200
- To: www-rdf-interest@w3.org
- Cc: dieter@cs.vu.nl, frankh@cs.vu.nl, horrocks@cs.man.ac.uk
Hi all, "Practical Knowledge Representation for the Web" (http://www.cs.vu.nl/~frankh/postscript/IJCAI99-III.html#Calvanese:98AAAI) because the paper Frank and I have been written did pop up again in the discussions I would like to make some general comments on it. 1. We wrote the paper at a point in time where we thought RDF aims on more that it actually does. We thought that it is meant as a web-based modelling language for meta data. Therefore, we critized RDF for lacking many features one would expect for a suitable modeling language. Meanwhile we learnt that RDF is "just" a syntax for writting down triples (very similar to a representation formalism covering only binary predicates). Clearly one could critique RDF for some of its design decisions, hard to read syntax, and explanation. However, having such a standard for writting down triples is a good thing anyway. 2. RDFS starts to be on a more interesting level because it introduces additional modeling primitives coming closer to a language that one would actually use for modeling meta data that are a bit more complex and structured than simple triple sets. Still, the primitives offered by RDFS are somehow limited and these choices are not really motivated. At least we fail to get these rationales from the scheme specification. 3. What we have done (in cooperation with many other research groups and industrials) was to define an Ontology Inference Layer OIL on top of RDFS (i.e., we define OIL as an extension of the name space of RDFS). More details can be found at http://www.ontoknowledge.org/oil. The main features of OIL are: - providing frame-based modelling primitives, because they are rather intiutive to most users; - defining a formal semantics and reasoning support based on Description Logics and the FaCT reasoning system; - defining a syntax based on RDF and RDFS (i.e., we define the extensions of OIL in RDFS). For people who do not want to follow the RDF(S) bandwaggon we also provide XML schema definitions of OIL. In consequence, we define an inference service layer on top of things like RDF and RDFS. Therefore, I think we closely follow the vision shared by many people (including Tim). Our early critique on RDF was based on the missunderstanding that we thought that already RDF should provide such a service. Greetings, Dieter ---- Dieter Fensel Division of Mathematics & Computer Science, Vrije Universiteit Amsterdam, De Boelelaan 1081a, 1081 HV Amsterdam, NL The Netherlands Room number U3.25. Tel.: +31-(0)20-444 7739, Fax and Answering machine: +31-(0)20-872 27 22 Mobil phone: +31-(0)6-51850619 Email: dieter@cs.vu.nl http://www.cs.vu.nl/~dieter Privat Liendenhof 64, NL-1108 HB Amsterdam, The Netherlands. Tel.: +31-(0)20-365 52 60.
Received on Wednesday, 12 April 2000 18:53:42 UTC