RE: URI thoughts

> Perhaps a concrete example could enlighten my difficulty in 
> understanding the value in:
> 
> 1) 'forcefully' attempting to dereference all URI terms in an 
> instance graph (which is what is described as a 'full' or 
> unrestricted Web Closure in http://esw.w3.org/topic/WebClosure)

Thanks, Chimezie.  I didn't know such definition exists.  This is related to
the "processing" model that I was wondering about.  It is important because
the same set of RDF statement will leads to different knowledge given
different closure.

Assuming I have a RDF model of the follows.

@prefix rdf: http://www.w3.org/1999/02/22-rdf-syntax-ns#.
@prefix dctype: http://dublincore.org/2003/12/08/dctype#

<http://www.charlestoncore.org/images/group-logo.png> rdf:type dctype:Image.

A simple model without any closure will contain only this one statement.  It
is not very useful, because given this model, I cannot even write a program
to tell a human that the resource
http://www.charlestoncore.org/images/group-logo.png is a "type" of "Image".
Note, the type and Image are annonated in their respective RDF document via
rdfs:label.  Without dereferencing the URI, you won't be able to obtain how
to label the graph and discribes it to a human.

But with the OntologicalClosure, the program would because the eventual
model to be processed would contain all RDF assertions after dereferencing
the rdf:type and dctype:Image.

Different types of closure gives you different scope of knowledge base, from
which different answers may be given to the same query.

I have tried to explain in the past the importance of ontology modulization.
Building a monolithic ontology, i.e., by putting all concepts under one
namespace, is VERY dangerous because dereferening one URI will in fact
retrieve all RDF statements under the same namespace. This will make the
sharing of ontology difficult.

This is also what prompt me to propose the concept of ontology
normalization.  But to avoid self-promotion, I will leave it to private
discussion if anyone is interested.

Xiaoshu

Received on Tuesday, 20 June 2006 18:54:26 UTC