- From: Antoine Zimmermann <antoine.zimmermann@deri.org>
- Date: Thu, 14 Oct 2010 18:16:11 +0200
- To: Jeremy Carroll <jeremy@topquadrant.com>
- CC: Toby Inkster <tai@g5n.co.uk>, Jesse Weaver <weavej3@rpi.edu>, semantic-web@w3.org
Jeremy, Le 14/10/2010 17:41, Jeremy Carroll a écrit : > Yes > > > The way to answer this is to assess the truth of > > rdfs:Literal rdfs:subClassOf owl:Thing . Well, this is one way of answering the question. I would say, this is the "proof-theoretic view". Another way of answering the question (which I would coin the "model-theoretic view") is to ask: are the interpretations of a rdfs:Literal included in the interpretations of owl:Thing? - in OWL DL: no! - in OWL Full: yes! - in RDF/RDFS: not determined (owl:Thing does not have a defined interpretation). In informal language, when people talk about things like literals or owl:Things, they often refer to the things in the interpretation domain (the things that they denote) and not of formulas. For instance, if I say "is the number 38 a rdfs:Literal?" I am not asking for the truth value of: "38"^^xsd:integer rdf:type rdfs:Literal . which, in RDF, RDFS, OWL DL and OWL Full, is a syntax error. > In some systems this is a syntax error. > In some systems this is necessarily true. > In no systems is this false. Nonetheless, I see your point: what matters in the end is what the system does. Note that it can be false in some systems: consider the following graph attached to a RDFS reasoner which supports D-entailment: ex:g { owl:Thing rdfs:subClassOf xsd:boolean . } With this graph, the triple rdfs:Literal rdfs:subClassOf owl:Thing is false. In case you consider the statement independently from any graph, then it is neither a syntax error, nor a true statement, in that system. Regards, -- Antoine Zimmermann Researcher at: Laboratoire d'InfoRmatique en Image et Systèmes d'information Database Group 7 Avenue Jean Capelle 69621 Villeurbanne Cedex France Lecturer at: Institut National des Sciences Appliquées de Lyon 20 Avenue Albert Einstein 69621 Villeurbanne Cedex France antoine.zimmermann@insa-lyon.fr http://zimmer.aprilfoolsreview.com/
Received on Thursday, 14 October 2010 16:16:46 UTC