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Re: RDF vocabulary definitions

From: Sandro Hawke <sandro@w3.org>
Date: Tue, 19 Nov 2002 22:48:11 -0500
Message-Id: <200211200348.gAK3mB328351@wadimousa.hawke.org>
To: David Menendez <zednenem@psualum.com>
cc: www-rdf-interest@w3.org


> At 9:17 AM -0800 2002-11-19, Richard H. McCullough wrote:
> >The two triples have the same meaning; either one implies the other.
> ><_:MyClass> <rdf:type> <rdfs:Class>
> ><_:MyClass> <rdfs:subClassOf> <rdfs:Class>
> 
> This is not my understanding of how RDFS defines these terms.
> 
> As a practical example, if I declare a class "Car", I would say:
> 
>    eg:Car rdf:type rdfs:Class.
> 
> If this implied that eg:Car is a subclass of rdfs:Class, then it 
> would mean that any instance of eg:Car is also a class.
> 
> Given:
>    eg:my_car rdf:type eg:Car.
>    eg:Car rdf:type rdfs:Class.
> Implies:
>    eg:Car rdfs:subClassOf rdfs:Class. # according to what you just said
>    eg:my_car rdf:type rdfs:Class.     # according to rdfs9
> 
> RDFS distinguishes between classes and class extensions. You could 
> create a system where my car is a class consisting of all cars that 
> are my car, but that's not how RDFS does it.

Ugh, indeed you're right.  Thanks for the clear and gentle correction.

These are true though, I think:

  x rdf:type rdfs:Property.   
  iff 
  x rdfs:subPropertyOf rdfs:Property.

and 
  
  x rdf:type rdfs:Class.  
  iff
  x rdfs:subClassOf rdfs:Resource.

and that little asymmetry was confusing me.

     -- sandro
Received on Tuesday, 19 November 2002 22:49:26 GMT

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