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Re: Comments on RDF Schema specification

From: Jeen Broekstra <jbroeks@cs.vu.nl>
Date: Thu, 15 Jun 2000 12:39:58 +0200 (MET DST)
To: Pierre-Antoine CHAMPIN <champin@bat710.univ-lyon1.fr>
cc: Michel Klein <mcaklein@cs.vu.nl>, www-rdf-comments@w3.org
Message-ID: <Pine.GSO.4.20.0006151216290.29634-100000@fluit.cs.vu.nl>
On Wed, 14 Jun 2000, Pierre-Antoine CHAMPIN wrote:

> Michel Klein wrote:
> > First, there was no way to overcome the restriction on the
> > rdfs:subClassOf statement, i.e. the restriction that no
> > cycles are allowed in the subsumption hierarchy.
> yes, there is :
> define a property oil:subClassOf which is a SUPERPROPERTY of
> rdfs:subClassOf, and which allows cycles !  You can still use
> rdfs:subClassOf if you know for sure that 2 classes are not
> equivalent, but if you are unsure (that is, if a cycle MAY
> occure), use oil:subClassOf.

This would solve the cycle-problem, yes. But there are a couple
of disadvantages to this approach:

 - a non-OIL-aware RDFS agent would not be able to understand
   that the oil:subClassOf relationship is essentially the same
   as rdfs:subClassOf. You would lose information on how the
   class hierarchy is built up.
 - a property is added that does not have any extra semantics,
   which we think is undesirable.

So basically, adding a oil:subClassOf relationship would be a
stop-gap measure. We thought it would be better to attack the
problem at the core ;)


                                                    Vrije Universiteit
Jeen Broekstra                 Dept. of Mathematics & Computer Science
jbroeks at cs.vu.nl                                  de Boelelaan 1081
http://www.cs.vu.nl/~jbroeks        1081 HV Amsterdam, the Netherlands
Received on Thursday, 15 June 2000 06:40:05 UTC

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