- From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
- Date: Wed, 23 Apr 2003 08:54:05 -0400 (EDT)
- 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="⪚hasDigit"/> > > <owl:cardinality rdf:datatype="&xsd;int">5</owl:cardinality> > > <owl:allValuesFrom rdf:resource="⪚Digit" /> > > <owl:someValuesFrom rdf:resource="⪚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 UTC