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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, 17 Nov 2011 09:41:51 +0100
Message-ID: <4EC4C8CF.3010705@emse.fr>
To: public-rdf-wg@w3.org

Le 16/11/2011 22:13, Richard Cyganiak a écrit :
> Hi Antoine,
> On 15 Nov 2011, at 21:23, Antoine Zimmermann wrote:
>>> if<bar>   owl:sameAs<baz>, and<baz>   is an IRI in the datatype
>>> map, then "foo"^^<bar>   may have a well-defined value even if
>>> the IRI<bar> is not in the datatype map.
>> Assuming that owl:sameAs was in the RDF/RDFS spec, this even would
>> not make "foo"^^<bar>  be interpreted identically as "foo"^^<baz>.
>> The interpretation of typed literals is not influenced by anything
>> in the ontology, even in OWL. "foo"^^<bar>  is always interpreted
>> as L2V(D(<bar>))("foo") according to the datatype map D.
>> FYI, look at section 4.2 of the OWL 2 RDF-based semantics:
>> "IL is a mapping from typed literals "s"^^u in V to their
>> denotations in IR, where IL("s"^^u) = L2V(d)(s), provided that d is
>> a datatype of D, IS(u) = d, and s is in the lexical space LS(d);
>> otherwise IL("s"^^u) is not in LV."
> That just requires that *d* (the datatype) is in the datatype map,
> not that *u* (the IRI) is in the datatype map. If I have<u>
> owl:sameAs<v>, then it follows that IS(u)=IS(v). If (v,d) is in the
> datatype map, then it follows that IS(v)=d, which gives us IS(u)=d
> without u being in the datatype map.
> That's how I read it anyways.

Damn, you're correct!

So I guess we have an agreement finally.


>> So the interpretation of "s"^^u (or "foo"^^<bar>) is in the value
>> space of<bar>  if and only if<bar>  is in the datatype map
> If my reasoning above is correct, then it doesn't require that<bar>
> is in the datatype map. It requires that<bar>  denotes d, and that d
> is in the datatype map.
>> Otherwise it is not in LV
> (That's actually not a requirement that I can find anywhere in RDF
> Semantics. RDF Semantics says that, if a literal's datatype IRI
> doesn't denote a datatype, then the literal “is treated as before”,
> it denotes “some unknown thing”. In other words, its denotation is
> entirely unconstrained, and interpretations that map the literal to a
> member of LV are fine. So the wording you quote looks a bit like a
> bug in OWL2 to me.)
>> I'm just saying that the word "value" may be misunderstood. For
>> instance, I would not consider a person to be a value.
> I don't think there's any basis for that. There's nothing *formally*
> wrong with defining a datatype whose lexical space is social security
> numbers, whose value space is citizens, and whose L2V mapping
> involves the social security database.
> Best, Richard

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, 17 November 2011 08:42:29 GMT

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