Thanks Pat to jump in this > > We could as well define a tautological class dcterms:Topic as the range of > dcterms:Subject, and assert only subclasses. > > Is that clearer? > > > What is not clear is why you want to do this. Even in the case of the > domestic appliances, if you do not put any necessary conditions on this > class, you have effectively said nothing. > OK. I'm certainly dumb, but in what is this different, say, from the definition of the class foaf:Agent at http://xmlns.com/foaf/spec/#term_Agent This class has no superclass, hence no necessary condition. Right? It has two declared subclasses foaf:Person and foaf:Organisation. Those provide sufficient conditions, hence nothing if I understand well. foaf:Agent the domain and range of some properties, but this again provides also sufficient conditions. Right? Would you say that foaf:Agent is not defined and even useless, since it has no necessary condition? The same for many top classes in many ontologies. No? Thanks for clarifying this. > It is tricky to appeal to intuition in cases like this, because of course > we all know that there are things that are not domestic appliances, and we > tend to use this knowledge without being told that we have to. But our > ontologies only know stuff like this if we somehow tell them it explicitly. > Indeed. Nobody argues on that :)) Bernard -- Bernard Vatant Senior Consultant Vocabulary & Data Engineering Tel: +33 (0) 971 488 459 Mail: bernard.vatant@mondeca.com ---------------------------------------------------- Mondeca 3, cité Nollez 75018 Paris France Web: http://www.mondeca.com Blog: http://mondeca.wordpress.com ----------------------------------------------------
Received on Wednesday, 9 September 2009 16:00:43 UTC