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Re: RDF-ISSUE-79 (undefined-datatype): What is the value of a literal whose datatype IRI is not a datatype? [RDF Concepts]

From: Antoine Zimmermann <antoine.zimmermann@emse.fr>
Date: Thu, 10 Nov 2011 15:41:20 +0100
Message-ID: <4EBBE290.1040702@emse.fr>
To: public-rdf-wg@w3.org
When RDF Concepts describe what the terms in RDF means, it must follow 
the RDF Semantics, which is (iii).  In RDF Semantics, 
"foo"^^http://ex.com/whatever  denotes a resource.  This resource can 
only be known according to a datatype map and only if the datatype map 
contains a pair (http://ex.com/whatever,ddd). Otherwise, it is unknown.

There is the notable exceptions of datatypes xsd:string and 
rdf:XMLLiteral, which must always be interpreted as required by XSD and 
RDF respectively (previously not true for xsd:string).

However, there is no way in RDF/RDFS to state that an IRI does not 
denote a datatype. The text should rather say something like:

"If <x,ddd> is not in the datatype map then a typed literal with 
datatype IRI x is interpreted as an unknown resource."

This requires that the notion of datatype map be introduced before.
Note that the unknown resource denoted by a literal of unsupported type 
may not be a literal value at all (e.g., it could be a person).


Le 09/11/2011 21:53, RDF Working Group Issue Tracker a écrit :
> RDF-ISSUE-79 (undefined-datatype): What is the value of a literal whose datatype IRI is not a datatype? [RDF Concepts]
> http://www.w3.org/2011/rdf-wg/track/issues/79
> Raised by: Richard Cyganiak
> On product: RDF Concepts
> The RDF Concepts spec (in both 2004 and 1.1 versions) does not answer the question what's the value of a literal where the datatype IRI doesn't actually denote a datatype, like<"foo",http://example.com/not-a-datatype>. This is surprising, as there is a section that normatively defines the value of *all other* literals.
> There are many possibilities:
> (i) the spec leaves it undefined
> (ii) that's not a valid RDF graph
> (iii) it's a valid RDF graph, but the value, if any, is unknown
> (iv) it's a valid RDF graph, and the literal is ill-typed
> This should be made explicit.
> The status quo is (i). I believe that the model theory says it's (iii).

Antoine Zimmermann
ISCOD / LSTI - Institut Henri Fayol
École Nationale Supérieure des Mines de Saint-Étienne
158 cours Fauriel
42023 Saint-Étienne Cedex 2
Tél:+33(0)4 77 42 66 03
Fax:+33(0)4 77 42 66 66
Received on Thursday, 10 November 2011 14:41:57 UTC

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