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Re: Domain/Range: conjuntion or disjuntion??

From: <tarod@softhome.net>
Date: Wed, 21 Nov 2001 14:10:38 GMT
Message-ID: <20011121141038.7011.qmail@softhome.net>
To: "Peter F. Patel-Schneider" <pfps@research.bell-labs.com>
Cc: brian_mcbride@hp.com, www-rdf-interest@w3.org, jena-dev@yahoogroups.com

Peter F. Patel-Schneider writes:

> From: tarod@softhome.net
> Subject: Domain/Range: conjuntion or disjuntion??
> Date: Wed, 21 Nov 2001 09:19:41 GMT
> 
> > 
> >   Hello Brian,
> > 
> >   With the old model, If I wanted to say that a property has as range a
> > class that must be a Car and a MotorCycle I could add to the schema.
> > 	<rdfs:Class rdf:about="http://some.com#CarsAndMotos">
> > 		<rdfs:subClassOf rdf:resource="http://some.com#Car"/>
> > 		<rdfs:subClassOf rdf:resource="http://some.com#MotorCycle"/>
> > 	</rdfs:Class>
> >   and change 1 for	
> > 	<rdf:Property rdf:about="http://some.com#owns">
> > 		<rdfs:domain rdf:resource="http://some.com#Person"/>
> > 		<rdfs:range rdf:resource="http://some.com#CarsAndMotos"/>
> > 	</rdf:Property>
> > 	
> >   now I can only have CarsAndMotos as range of the property own and because
> > 
> >   SubClass(CarsAndMotos, Car) and SubClass(CarsAndMotos, MotorCycle);
> >   Range(own, CarsAndMotos);
> > 
> >   Range(x, y) and SubClass(z, y) -> Range(x, z);
> >   
> >   Range(own, Car) and Range(own, MotorCycle) !!!!!! THAT's what you wanted,
> > isn't it?
> 
> No.  CarsAndMotos is not the same as the intersection of Car and
> Motorcycles.  It is possible to have an object that is both a Car and a
> Motorcycle, but not a CarsAndMotos.
> 
> So, in some sense, and remembering the expressive impoverishment of RDFS,
> the expressive power of the disjunctive view and the expressive power of
> the conjunctive view are incomparable.  There are tricks that can be played
> in RDFS to get part of the difference back, but the difference is only
> eliminated if you have true disjunction and conjunction as concept-forming
> operators.
> 
> Peter F. Patel-Schneider
> Bell Labs Research


  I'm sorry, I don't understand the part 'concept-formint operators' what
do you mean?

  What I wanted to explain is that a object CarsAndMotos must be instanceOf
Car and instance of MotorCycle, so the 'trick' we use here works as we
wish, but an instance of Vehicle should not be instance of Car neither
MotorCycle, so the trick proposed here doesn't work.

      - Marc
Received on Wednesday, 21 November 2001 09:45:18 GMT

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