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Re: Comments on RDF Schema specification

From: Pierre-Antoine CHAMPIN <champin@bat710.univ-lyon1.fr>
Date: Wed, 14 Jun 2000 17:42:00 +0200
Message-ID: <3947A7C8.122BEA69@bat710.univ-lyon1.fr>
To: Michel Klein <mcaklein@cs.vu.nl>, www-rdf-comments@w3.org
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.

it's just an idea, anyway... I agree with you that rdfs:subClassOf SHOULD accept cycles ;-)

> Second, in contrast with RDFS, OIL allows more than one range restriction
> on a property.

this would be nice too, I agree.

I think RDFS was designed with the idea of allowing schema-validation,
that's why RDFS properties are over-constraining. (subClassOf, range...)
Note the post from Ralph Swick suggesting to disallow multiple domains...
  http://lists.w3.org/Archives/Public/www-rdf-interest/2000Jun/0018.html
In an open world hypothesis, allowing multiple constraint properties make them no more constraining, only indicative... that does not bother me, but it seems to bother Ralph.

  Pierre-Antoine

--- Quid quid Latine dictum sit, altum viditur
    Whatever is said in Latin sounds important.
Received on Wednesday, 14 June 2000 11:43:02 GMT

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