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Re: DAML-ONT: the case for closedness

From: Jeff Heflin <heflin@cs.umd.edu>
Date: Fri, 20 Oct 2000 10:34:34 -0400
Message-ID: <39F057FA.F4D1ABCC@cs.umd.edu>
To: "Hart, Lewis" <lhart@grci.com>
CC: www-rdf-logic@w3.org
"Hart, Lewis" wrote:
> 
> It is not the same Thing (pun intended). Remember that there are multiple
> namespaces involved. A more exact summary of the ontological statements
> above
> might be, for the valid case:
> 
> ec:Product isa daml:Thing
> ec:Computer isa ec:Product
> qco:QuantumComputer isa ec:Computer
> qco:Q2000 instance-of qco:QuantumComputer
> 
> and for the invalid one:
> 
> bad:Thing isa ec:Computer
> 
> Four different ontologies are in use here: DAML (daml:), eCommerce (ec:),
> the QuantumComputerOntology (qco:) and the bogus one (bad:).  What was
> actually
> said is not all dmal:Things are ec:Computers but just all bad:Things
> are ec:Computers. Perhaps this is not even bad in itself, if all that
> this ontology discusses are in fact computers.
> 

Thanks for bringing up the point about namespaces. I should have been
clearer in my example. Still, due to the way RDF and namespaces work,
the "bad" ontology really can say:

daml:Thing isa ec:Computer

Here's what it looks like in RDF (assuming http:/www.daml.org/damlont
and http:/www.commerce.org/econt are the daml and ec namespaces from
above):

<rdf:Description about="http://www.daml.org/damlont#Thing">
   <rdfs:subClassOf resource="http://www.commerce.org/econt#Computer" />
</rdf:Description>

This is an unfortunate consequence of RDF's "anyone can say anything
about anything" property." Thus, trust becomes 100 times more important
for ontologies than it does for ordinary RDF documents. If you
mistakenly trust a plain RDF document, at worst you may believe a
hundred false assertions. If you mistakenly trust an ontology, all of
your subsequent beliefs could turn out to be wrong!

Jeff
Received on Friday, 20 October 2000 10:28:51 GMT

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