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Re: Subclass of Thing/Resource

From: William Grosso <grosso@SMI.Stanford.EDU>
Date: Tue, 29 Feb 2000 16:00:02 -0800
Message-ID: <38BC5D82.33FE42E4@smi.stanford.edu>
To: Dan Brickley <Daniel.Brickley@bristol.ac.uk>
CC: Tim Berners-Lee <timbl@w3.org>, www-rdf-interest <www-rdf-interest@w3.org>


Dan Brickley wrote:
> 
> On Tue, 29 Feb 2000, Tim Berners-Lee wrote:
> > In RDF, every class is a subclass of rdfs:Resource so surely that is just as
> > informationless too.
> > (I do wish RDF had used "thing" instead of "resource" which has a meaning in
> > URI already).
> >
> > TimBL
> 
> So... are there identifiable 'things' that aren't 'resources'? (do you
> mean the Literals?). The RDFS design on this pretty much followed from the RDF
> Model claim that we inhabit the Web's world of URI-nameable resources...
> 

Hi, 

Sorry for the confusion about :Thing. There are many answers here.
One is that:

        Every class you define using protege, in an RDF project, should
        be a subclass of rdfs:Resource.

Another is that classes which are not subclasses of rdfs:Resource, but
which are subclasses of :Thing, are useful for data elements which are
not Protege primitives (roughly: int, float, string, symbol, boolean) and
which are not resources in RDF. Right how, this is "URI", but in the
worl dof the not-so-distant future, this is (If I read the Cambridge 
Communique correctly), going to include the XML Schema primitives.

Yet another point, which TBL made is that :Thing is redundant in the
persistence format. That is, yuo could make the assumption that
"any class which does not have a superclass is attached to :Thing" and
have a perfectly valid storage format.

In our CLIPS legacy format, we explicitly write out that everything is 
a subclass of the base class (which is actually "USER" in CLIPS) because 
otherwise the expert system shell won't parse the file. 

In our RDF format, we do omit this information, unless the user has 
explicitly asserted the parentage (e.g. directly attached the class to 
:Thing). 

Perhaps we should omit the :Thing ?


-weg


> Could you say something about what you'd count as a non-resource 'thing'?
> (or is it a concern that we've coupled the RDF terms to concepts
> defined, and argued about, elsewhere...?)
> 
> --dan
Received on Tuesday, 29 February 2000 19:00:07 GMT

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