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semantics issue with respect to RDF model theory

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Thu, 20 Mar 2003 14:13:59 -0500 (EST)
Message-Id: <20030320.141359.133037751.pfps@research.bell-labs.com>
To: www-webont-wg@w3.org


Currently the RDF model theory says that in a D-interpretation
that ICEXT(I(rdfs:Datatype)) is a subset of the set of datatypes of D.

This means that in an XSD-interpretation
	xsd:integer rdf:type rdfs:Datatype .
does not follow from the empty graph.
It also means that if you add more datatypes, you get more interpretations,
which violates the datatype monotonicity lemma.

I believe that there needs to be a different relationship between 
ICEXT(I(rdfs:Datatype)) and the set of datatypes of D, namely that 
ICEXT(I(rdfs:Datatype)) is a superset of the set of datatypes of D.

This would mean that in an XSD-interpretation (and in an OWL
interpretation) 
	xsd:integer rdf:type rdfs:Datatype .
*does* follow from the empty graph.

I suggest that the Web Ontology Working Group
1/ include the above as a test case,
2/ mention to the RDF Core WG that OWL has a test case that violates the
   RDF model theory, and
3/ suggest that the appropriate fix is as I describe above.  (There would
   have to a non-trivial amount of change required to the RDF Semantics
   document to make this fix.)

Peter F. Patel-Schneider
Bell Labs Research
Lucent Technologies
Received on Thursday, 20 March 2003 14:30:16 GMT

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