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Re: The semantics of rdfs:label

From: Christopher Welty <welty@us.ibm.com>
Date: Wed, 14 Sep 2005 11:43:30 -0400
To: danbri@w3.org
Cc: "Lars Marius Garshol" <larsga@ontopia.net>, public-swbp-wg@w3.org, public-swbp-wg-request@w3.org
Message-ID: <OF75A96D2C.7009E03A-ON8525707C.0055CAAC-8525707C.00566192@us.ibm.com>

There is a simple solution here, that let's you use the best of both 

OWL DL tools do not "opt out" of rdfs:label.  What OWL-DL prevents is 
using rdfs:label in a subProperty relation.  If you separate your 
vocabulary into two files, including in one everything that is legal 
OWL-DL and in the second the statements that are OWL-Full only, then you 
are fine.  The OWL-Full file imports the OWL-DL file.  Only import the DL 
file when you want to use OWL-DL tools.  rdfs:label is perfectly valid in 
OWL-DL (it just isn't used in reasoning, but it doesn't go away or 
anything).  Your foaf:name subPropertyOf rdfs:label statement will go in 
the OWL-Full file and can be imported by visualization tools such as the 
one you mention.

We use this approach all the time, although as I said previously we prefer 
not to use rdfs:label in a property hierarchy.


Dr. Christopher A. Welty, Knowledge Structures Group
IBM Watson Research Center, 19 Skyline Dr., Hawthorne, NY  10532
Voice: +1 914.784.7055,  IBM T/L: 863.7055, Fax: +1 914.784.7455
Email: welty@watson.ibm.com
Web: http://www.research.ibm.com/people/w/welty/

Sent by: public-swbp-wg-request@w3.org
09/14/2005 09:35 AM

"Lars Marius Garshol" <larsga@ontopia.net>
Re: The semantics of rdfs:label

> There is an important point about the human semantics of rdfs:label
> that is not clear to the RDFTM task force, and which is very important
> for us.
> The RDFS specification says about rdfs:label that it
>   "may be used to provide a human-readable version of a resource's
>   name."
> This makes it sound as though this is the common super-property of all
> RDF properties with name semantics, such as dc:title, foaf:name,
> skos:prefLabel, etc

It has also been used in that way in the Dublin Core community
(with some overlap with the relatively obscure/neglected and
underspecified rdf:value property).

> However, some people tell us that this is not the case, and it
> certainly doesn't seem obvious that this is the case.
> Does anyone know? Is there an official answer to this question?

W3C is a meeting place for many overlapping communities. Some (such
as those working with Description Logics) prefer to maintain a
strict separation between ontology/schema layers and instance data,
and hence consider rdfs:label as unsuited to instance data usage; the
OWL specs say that it is an AnnotationProperty, ie. a decoration used
in vocab descriptions). There are however tools which make use of
rdfs:label as an instance level naming property, for example Damian
Steer's BrownSauce RDF browser,
http://www.xml.com/pub/a/2003/02/05/brownsauce.html which uses it
to provide user-facing labels for resources that might otherwise have
nothing more than URIs to present in a UI. FOAF's claim that { foaf:name
rdfs:subPropertyOf rdfs:label } is made with such tools in mind. It has
generated a few mails to me (as FOAF namespace editor) along lines of
"hey, you should be OWL DL compatible if you want to _really_ be part of
the Semantic Web". That attitude strikes me as over-zealous and 
but reflects a genuine division in the community and mismatch amongst
tools --- by not being DL-based, we opt out of a number of handy tools.
By being DL-based we lose out on other tools (such as rdfs:label). I don't
believe that a "Best Practice" is clear, and welcome advise from other WG
members. Note also that this is an active topic of discussion in the
Dublin Core world, where we're trying to figure out a migration path 
less string-centric descriptions of things like creators, publishers



> --
> Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
> GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >
Received on Wednesday, 14 September 2005 15:44:40 UTC

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