- From: David Menendez <zednenem@psualum.com>
- Date: Fri, 14 May 2004 01:33:10 -0400
- To: "Burkett, Bill" <WBurkett@modulant.com>
- Cc: Benja Fallenstein <b.fallenstein@gmx.de>, www-rdf-interest@w3.org
Burkett, Bill writes:
> "(-" = "member of"
> "<" = "subclass of"
>
> Using my example again:
> m (- M
> M (- C
> M < C
>
> The problem I have is an apparent contradiction in the latter two
> statements with respect to m. As a member of C, members of M are
> *not* also members of C. As a subclass of C, members of M *are* also
> members of C. Is this where we find the Incompleteness of our
> rdf/rdfs representational langauge? Is this an inherent
> paradox/contradiction that we just have to live with?
The problem is the assumption that instances of M cannot be instances of
C. In RDF, a class is an entity associated with a set of instances, not
the set of instances itself.
Consider this:
ex:Species rdf:type rdfs:Class.
ex:Species rdfs:subClassOf rdfs:Class.
ex:Orangutan rdf:type ex:Species.
ex:koko rdf:type ex:Orangutan.
If we write the extension of the class C as IEXT(C), we have:
IEXT(rdfs:Resource) = { rdfs:Resource, rdfs:Class, ex:Species,
ex:Orangutan, ex:koko, ... }
IEXT(rdfs:Class) = { rdfs:Resource, rdfs:Class, ex:Species,
ex:Orangutan, ... }
IEXT(ex:Species) = { ex:Orangutan }
IEXT(ex:Orangutan) = { ex:koko }
--
David Menendez <zednenem@psualum.com> <http://www.eyrie.org/~zednenem/>
Received on Friday, 14 May 2004 01:37:17 UTC