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Re: Case for Reinstatement of Qualified Cardinality Restrictions

From: Guus Schreiber <schreiber@cs.vu.nl>
Date: Wed, 23 Apr 2003 11:08:22 +0100
Message-ID: <3EA66616.2070802@cs.vu.nl>
To: Jeff Heflin <heflin@cse.lehigh.edu>
CC: webont <www-webont-wg@w3.org>

Jeff Heflin wrote:

[..]

> 3) I think the factor that makes QCRs most confusing in OWL is the
> difficulty in expressing them cleanly in triples. Currently, the
> Restriction class is a place to hang each restriction that is applicable
> to a property. Currently, each of these is a binary predicate so the
> following is perfectly fine.
> 
> <owl:Restriction>
>   <owl:onProperty rdf:resource="&eg;hasDigit"/>
>   <owl:cardinality rdf:datatype="&xsd;int">5</owl:cardinality>
>   <owl:allValuesFrom rdf:resource="&eg;Digit" />
>   <owl:someValuesFrom rdf:resource="&eg;Finger" />
> </owl:Restriction>
> 

This is not "perfectly fine". OWL currently allows only one single value 
or cardinality constraint witrhin a restriction class (se the relevant 
sections in S&AS and Ref). I agree that allowing QCRs would probably 
mean we have to intriduce restriction classes with two constraints on a 
property, but they can, in principle, be semantically distinguished from 
the single-statement constraints.

Guus

[..]

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Received on Wednesday, 23 April 2003 06:08:27 GMT

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