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Re: Case for Reinstatement of Qualified Cardinality Restrictions

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 23 Apr 2003 08:54:05 -0400 (EDT)
Message-Id: <20030423.085405.22924579.pfps@research.bell-labs.com>
To: schreiber@cs.vu.nl
Cc: www-webont-wg@w3.org

From: Guus Schreiber <schreiber@cs.vu.nl>
Subject: Re: Case for Reinstatement of Qualified Cardinality Restrictions
Date: Wed, 23 Apr 2003 11:08:22 +0100

> 
> 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). 

Huh?  OWL allows an arbitrary number of restriction triples (onProperty,
cardinality, etc.) to have the same subject.  Sometimes OWL gives no extra
meaning to these restrictions; sometimes OWL gives the extra meaning that
one would expect; sometimes OWL gives unusal extra meaning to these
restrictions.  In particular, Jeff's example is one case where the meaning
given to a restriction by OWL is decidedly unusal.

It would have been much nicer if this was not the case, but our hands were
tied.

[...]

> Guus
> 
> [..]

peter
Received on Wednesday, 23 April 2003 08:54:15 GMT

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