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Re: Questions on RDF mapping of OWL 2 data ranges

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Mon, 9 Nov 2009 18:23:18 -0500
Message-ID: <29af5e2d0911091523i2e80f84qa84a17523e5bbbb9@mail.gmail.com>
To: Holger Knublauch <holger@topquadrant.com>
Cc: public-owl-dev@w3.org, Michael Schneider <schneid@fzi.de>
On Mon, Nov 9, 2009 at 4:06 PM, Holger Knublauch <holger@topquadrant.com> wrote:
> Dear group,
>
> I am unsure about the right (and best) way of mapping user-defined OWL 2
> datatypes to RDF graphs. I have been skimming through the OWL specs but all
> examples I saw were of the following format (see
> http://www.w3.org/TR/2009/REC-owl2-syntax-20091027/#Datatype_Definitions):
>
>        a:SSN rdf:type rdfs:Datatype .
>        a:SSN owl:equivalentClass _:x .
>        _:x rdf:type rdfs:Datatype .
>        _:x owl:onDatatype xsd:string .
>        _:x owl:withRestrictions ( _:y ) .
>        _:y xsd:pattern "[0-9]{3}-[0-9]{2}-[0-9]{4}" .
>
> This means that a datatype is an instance of rdfs:Datatype that has an
> owl:equivalentClass of another (anonymous) datatype which then points to the
> fact restrictions as an rdf:List.
>
> 1) Would it also be allowed to use rdfs:subClassOf instead of
> owl:equivalentClass?

No. The mappings are defined precisely in
http://www.w3.org/TR/2009/REC-owl2-mapping-to-rdf-20091027/

> 2) Would it be legal to attach the restrictions directly on the named
> datatype instead of going through the (very verbose!) blank node, e.g.
>
>        a:SSN rdf:type rdfs:Datatype .
>        a:SSN owl:onDatatype xsd:string .
>        a:SSN owl:withRestrictions ( _:y ) .
>        a:SSN xsd:pattern "[0-9]{3}-[0-9]{2}-[0-9]{4}" .

No. If you don't see a mapping rule to create or parse such triples in
the mapping document, then the construct isn't syntactically correct.
If you wrote the above it wouldn't mean what you intend it to mean.


> 3) Is it legal (and good practice) to subclass existing datatypes, such as
>
>        a:SNN rdfs:subClass xsd:string .

Not legal in OWL-DL. If you look at the reverse mapping the
consequence of this is that a:SNN and xsd:string will be considered
classes, not datatypes and that a term can't denote both a class and
datatype.

In OWL Full, this is allowed, but I wouldn't consider it good practice
- however perhaps Michael Schneider has a different opinion? ccing
him.

-Alan

>
> Thanks for clarifying these, so that we can built the best practices into
> our tools.
> Holger
>
>
>
Received on Monday, 9 November 2009 23:24:14 GMT

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