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RE: Qualified Cardinality Restrictions

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Mon, 28 Apr 2003 12:54:35 +0100
Message-ID: <16045.5755.460926.758387@galahad.cs.man.ac.uk>
To: "Jeremy Carroll" <jjc@hplb.hpl.hp.com>
Cc: <www-webont-wg@w3.org>

On April 28, Jeremy Carroll writes:
> 
> I am not sure this proposal is monotonic, maybe I have misunderstood ...
> 
> >
> > RDF Graphs
> > ==========
> >
> > Again, the obvious solution seems to be to combine some values from
> > and cardinality into a single mapping. Simple cardinality constraints
> > can then use the same mapping with the qualifying class set to
> > owl:Thing, while someValuesFrom can use the minValuesFrom mapping with
> > the cardinality set to 1. There are two obvious possibilities for the
> > mapping, i.e., attaching the min/max/blank to the valuesFrom property
> > name or to the cardinality property name. The first of these seems
> > more consistent with the above abstract syntax.
> >
> > E.g., minVaulesFrom using the valuesFrom property to indicate the "min":
> >
> > restriction(ID minValuesFrom(required min))   _:x rdf:type
> > owl:Restriction .
> > _:x rdf:type owl:Class . [opt]
> > _:x rdf:type rdfs:Class . [opt]
> > _:x owl:onProperty T(ID) .
> > _:x owl:minValuesFrom T(required) .
> > _:x owl:cardinality "min"^^xsd:nonNegativeInteger .
> >
> > or using the cardinality property to indicate the "min":
> >
> > restriction(ID valuesFrom(required min))   _:x rdf:type owl:Restriction .
> > _:x rdf:type owl:Class . [opt]
> > _:x rdf:type rdfs:Class . [opt]
> > _:x owl:onProperty T(ID) .
> > _:x owl:valuesFrom T(required) .
> > _:x owl:minCardinality "min"^^xsd:nonNegativeInteger .
> >
> >
> 
> If we retain the current RDF graph syntax
> _:x rdf:type owl:Restriction .
> _:x owl:onProperty T(ID) .
> _:x owl:cardinality "min"^^xsd:nonNegativeInteger .
> 
> >
> > or using the cardinality property to indicate the "min":
> >
> _:x rdf:type owl:Restriction .
> _:x owl:onProperty T(ID) .
> _:x owl:minCardinality "min"^^xsd:nonNegativeInteger .
> 
> 
> Then I believe that adding the extra triple as suggested is non-mon.
> 
> 
> Maybe the proposal is that the current (RDF graph) syntax for cardinality
> constraints is dropped and all such restrictions have to be qualified (e.g.
> to owl:Thing) - this would be monotonic, but a bit of a drag.

If we want to retain the current (RDF graph) syntax for cardinality
then you are probably right about the non-mon problem. We could fix
this by inventing an new property for cardinality in the QCR case,
e.g.:

restriction(ID minValuesFrom(required min))   _:x rdf:type
owl:Restriction .
_:x rdf:type owl:Class . [opt]
_:x rdf:type rdfs:Class . [opt]
_:x owl:onProperty T(ID) .
_:x owl:minValuesFrom T(required) .
_:x owl:valueCardinality "min"^^xsd:nonNegativeInteger .

This is also a bit of a drag though in terms of having
excessive/redundant syntax. Remember that the existing form of
unqualified cardinality restriction can be written as:

restriction(ID minCardinality(min))   _:x rdf:type
owl:Restriction .
_:x rdf:type owl:Class . [opt]
_:x rdf:type rdfs:Class . [opt]
_:x owl:onProperty T(ID) .
_:x owl:minValuesFrom owl:Thing .
_:x owl:cardinality "min"^^xsd:nonNegativeInteger .


I appreciate that this would involve more extensive changes to
existing documents, which may be (highly) undesirable!

Ian




> 
> Jeremy
> 
Received on Monday, 28 April 2003 07:45:32 GMT

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