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Re: P.S. re: two senses of Class (RDF vocabulary definiitions)

From: David Menendez <zednenem@psualum.com>
Date: Wed, 20 Nov 2002 01:52:54 -0500
Message-Id: <a05111b09ba00dcf55a89@[10.0.1.2]>
To: "RDF-Interest" <www-rdf-interest@w3.org>
At 10:16 PM -0800 2002-11-19, Richard H. McCullough wrote:
>I had forgotten about the other problem with type, e.g.
>
>     John Doe  type  person
>
>where
>
>     John Doe  individualOf  person
>
>not
>
>     John Doe  subClassOf  person

I'm not sure what problem you're seeing.

In RDF(S), the statements
   eg:john_doe rdf:type eg:Person.
and
   eg:john_doe rdf:subClassOf eg:Person.
are entirely independent and mean different things.

My understanding of RDF-MT is that the first statement means 
"I(eg:john_doe) is a member of ICEXT(I(eg:Person))" while the second 
means "ICEXT(I(eg:john_doe)) is a subset of ICEXT(I(eg:Person))". 
These are distinct assertions, and either can be true without the 
other being true.

(I(x) is the interpretation of x, and ICEXT(y) is the set of all 
things belonging to the class y.)

If I say
   eg:Dog rdfs:subClassOf eg:Mammal.
I am not implying
   eg:Dog rdf:type eg:Mammal.
because that would mean that the class "Dog" is a mammal, which it is 
not. Individual dogs are mammals, but the set of all dogs is a set.
-- 
Dave Menendez - zednenem@psualum.com - http://www.eyrie.org/~zednenem/
Received on Wednesday, 20 November 2002 01:51:31 GMT

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