On mån, 2007-02-26 at 11:11 +0100, Ivan Herman wrote:
> Hi Mikael,
> Thanks for this pointer. I looked through the examples, so let me ask
> the following. I understand that you can write
>
> <rdf:Description rdf:about="http://example.org/123">
> <dc:subject rdf:resource="http://example.org/subject32"/>
> </rdf:Description>
right.
>
> or it can become more complicated, like:
>
> <rdf:Description rdf:about="http://example.org/123">
> <dc:subject>
> <ex:ExampleSubjects rdf:about="http://example.org/subject32">
> <dcrdf:valueString xml:lang="en">Biology</dcrdf:valueString>
> <dcrdf:valueString
> rdf:datatype="http://example.org/taxonomy/SubjectEncoding">
> EA32
> </dcrdf:valueString>
> </ex:ExampleSubjects>
> </dc:subject>
> </rdf:Description>
Yes, except dcrdf:valueString will probably become just rdf:value in the
next draft.
>
> But does it mean that you will no longer be allowed to use:
>
> <rdf:Description rdf:about="http://example.org/123">
> <dc:subject
> rdf:datatype="http://example.org/taxonomy/SubjectEncoding">EA32</dc:subject>
> </rdf:Description>
Again, for the dc: properties, you will be able to do more or less what
you want.
There will be a new property, called dcterms:subject. Now, this new
property won't have a restricted range, as more or less anything can be
used as the "subject" of a resource, so it's actually open for all kind
of uses too.
>
> Or, as a really simple case:
>
> <rdf:Description rdf:about="http://example.org/123">
> <dc:subject>something</dc:subject>
> </rdf:Description>
>
> The problem I have is that *most* (non-librarian) users of DC will still
> use the pure and simple literal. How will you accomodate with that?
Use the dc: terms in all such cases, and you don't have to change one
thing...
> Maybe you should have dc:subject and dc:complexSubject when necessary.
We will have dc:subject and dcterms:subject.
> For other predicates, some sort of an owl:unionOf might be hand to
> define precise range. I am not sure. But what I know that for *lot* of
> people the combination with the value String is a little bit too
> complicated.
>
> [Actually, I have the impression that what you are fighing with here is
> the fact that one cannot use a literal in a subject position in RDF.
> Some would like to remove this restriction, but, well, when and how this
> issue will be reopened nobody knows...]
Well, partly that, but mostly the fact that, for example, the creator of
a resource is never a string, but a person, and we want that reflected
in the model. The issue is that dc: properties aren't very useful for
many RDF uses, simply because one does not know whether to expect a
literal or non-literal as value of a given property.
Please have a further look at
http://dublincore.org/documents/dc-rdf-notes/
that accompanied the dc-rdf draft you read above.
/Mikael
>
> Ivan
>
>
> > which is still not fully up-to-date with these DCAM modifications, but
> > gives you an idea of the direction.
> >
> > In short, we want DC to fully interoperate in an RDF world, while still
> > being just as useful in other contexts (OAI etc),
> >
> > /Mikael
> >
> >
>
> --
>
> Ivan Herman, W3C Semantic Web Activity Lead
> URL: http://www.w3.org/People/Ivan/
> PGP Key: http://www.cwi.nl/%7Eivan/AboutMe/pgpkey.html
> FOAF: http://www.ivan-herman.net/foaf.rdf
--
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Plus ça change, plus c'est la même chose
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