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Re: Subclass of Thing/Resource

From: Ray Fergerson <fergerson@SMI.Stanford.EDU>
Date: Tue, 29 Feb 2000 14:41:08 -0800
Message-ID: <38BC4B04.FFF3BBA1@smi.stanford.edu>
To: Tim Berners-Lee <timbl@w3.org>
CC: www-rdf-interest@w3.org, Stefan Decker <stefan@DB.Stanford.EDU>

Protege has a root class :THING and a subclass of :THING called rdfs:Resource. 
We considered making rdfs:Resource an alias of :THING but we could not because
rdfs:Resource has properties (such as "isDefinedBy" and "seeAlso").  Thing has
no properties (other than "name" which some would call a property).  Thus we had
to have two separate classes.  Now all RDF users should probably only subclass
rdfs:Resource but they are not prevented from subclassing :THING directly.  If
they do so then this information needs to be preserved.  This is the point that
Stefan is trying to make.


Tim Berners-Lee wrote:
> From: Stefan Decker <stefan@db.stanford.edu>
> >if an application  does not know protege:thing, it can ignore it.
> Surely, if it does *not* know protege:thing it *cannot* ignore it without
> throwing away information.
> If it *does* know protege:thingthen it *can* ignore the statement as it
> knows it contains no information.  Every class is a subclass of Thing.
> >If a user defines a resource to be a subclass of protege:Thing, protege can
> >not ignore this and we have to save that.
> No, you can just hang all classes not defined as subclasses of anything else
> off the "thing" hook in the UI.
> >However,  i think there is a small missunderstanding: you probably meant
> >that #Calendar is a subclass of rdfs:Resource.
> 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).
Received on Tuesday, 29 February 2000 17:40:03 UTC

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