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RE: RDF vocabulary definitions

From: Jon Hanna <jon@spin.ie>
Date: Tue, 19 Nov 2002 17:50:40 -0000
To: <www-rdf-interest@w3.org>
Message-ID: <NDBBLCBLIMDOPKMOPHLHAENLEJAA.jon@spin.ie>

> The two triples have the same meaning; either one implies the other.
>
> <_:MyClass> <rdf:type> <rdfs:Class>
> <_:MyClass> <rdfs:subClassOf> <rdfs:Class>

Are you sure?

The first indicates that MyClass is a category of "thing" in some shape or
form.
The second indicates that MyClass is a category of category of "thing".

I can see how one can say that the second implies the latter (since
"category of thing" is itself a "thing"), but not how the first implies the
former.

I'd be grateful if you could explain this, preferably using either natural
language or with reference to the RDFS closure concept described in rdf-mt
(any other notation is likely to leave me at a loss).

For the record, in terms of RDFS closures going from the latter to the
former is easy once we add the triple <rdfs:Class> <rdf:type> <rdfs:Class>:

<xxx> <rdfs:subClassOf> <yyy> .
<aaa> <rdf:type> <xxx> .
entails
<aaa> <rdf:type> <yyy> .

hence:

<_:MyClass> <rdfs:subClassOf> <rdfs:Class> .
<rdfs:Class> <rdf:type> <rdfs:Class> .
entails
<_:MyClass> <rdf:type> <rdfs:Class> .
Received on Tuesday, 19 November 2002 12:44:00 GMT

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