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RE: Indicating Closure ("and that's all there is")

From: Stephen Cranefield <SCranefield@infoscience.otago.ac.nz>
Date: Fri, 7 Dec 2001 14:33:51 +1300
Message-ID: <B57613845A50D211864C0000F8FA5C2804207830@mars.otago.ac.nz>
To: "'Sandro Hawke'" <sandro@w3.org>, www-rdf-interest@w3.org
Sandro Hawke wrote:
> RDF has an "anyone can say anything about anything" philosophy that
> seems deeply at odds with the practical need to list a specific set of
> properties and by omission negate all others.  If I'm listing my car
> for sale in RDF, I can list the repair work that has been done to it,
> but I cannot say that this is all the repair work.

...

> I'd rather just find a way to say "and that's all" or "here's the edge
> of the world", but I don't know how to do that. 
> 
> Has anyone solved this problem?  

In my paper "UML and the Semantic Web" at
http://www.semanticweb.org/SWWS/program/full/paper1.pdf (Section 5)
I proposed the use of a property notClosedOn defined as follows:
A statement <p, notClosedOn, r> is a declaration that there may
exist some statements <r, p, r'> that are known to hold but which
aren't included in the model.  The absence of a notClosedOn statement
means that it can be assumed that complete information is given for
property p applied to subject r.  An equally viable alternative
approach would be to assume that all information is *incomplete*
except where a ClosedOn statement specifies otherwise.

This is similar to mechanisms in knowledge representation systems
such as LOOM and CLASSIC, and to "local closed world" formulae in AI
planning.  To do this properly requires having a ternary property
(or an RDF simulation of one) relating the model, property and
a resource, but unfortunately RDF does not yet have a standard way
of referring to a model or context.

By the way, despite the title of the paper cited above, this part
of it doesn't depend on whether or not the ontology was defined using
UML and then translated to RDF Schema.

- Stephen
Received on Thursday, 6 December 2001 20:30:02 GMT

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