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Re: LANG: owl:ontology

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Tue, 17 Sep 2002 22:28:55 -0400 (EDT)
Message-Id: <20020917.222855.65682009.pfps@research.bell-labs.com>
To: hendler@cs.umd.edu
Cc: phayes@ai.uwf.edu, www-webont-wg@w3.org

From: Jim Hendler <hendler@cs.umd.edu>
Subject: Re: LANG: owl:ontology
Date: Tue, 17 Sep 2002 21:57:21 -0400

[...]

> [W]hat I have a problem with is the following
> 
> At URI1:
> ....
> <owl:class rdf:ID="foo" />
> 
> (1,000,000 other assertions that appear in the graph)
> 
> At URI2:
> 
> <:bar owl:subclass URI1:foo />
> 
> (put in any owl:ontology and rdf:RDF syntax you want - but no 
> owl:imports in URI2:)
> 
> In this case I have a real problem with merging the graphs -- the 
> user is very unlikely to actually intend that those million facts 
> which he or she may not even have read should be included.
> 
> This is the case I really care about.  For imports anything that can 
> identify and merge graphs makes me happy - for this case, I care that 
> we somehow scope what is included.  I would like this to have the 
> same semantics as having one URI which contained
> 
> <owl:class rdf:ID="foo" />
> <:bar owl:subclass :foo />
> 
> (i.e. nothing else from URI1: is to be included unless it is 
> explicitly  mentioned.)

Sure, but where do you draw the line?  

I can see no way of drawing the line in an RDF graph *at all*.  I can see
no way of drawing the line in an RDF/XML document *at all*, even if it is a
translation from OWL abstract syntax.  I can even only see broken ways of
drawing the line in the OWL abstract syntax.

Actually your example is a particularly bad one, because the contents of
URI2 by itself implies that URI1:foo is an OWL class (or at least it would
if OWL had a relationship like owl:subclass.  A much better example would
be 
At URI1:
	....
	:foo rdfs:subClassOf :bax .
	(1,000,000 other assertions that appear in the graph)
At URI2:
	:bar rdfs:subClassOf URI1:foo .
but then suppose URI1 contains
	:bax rdfs:subClassOf :bbb .
How can you exclude this triple?

Peter F. Patel-Schneider
Bell Labs Research
Received on Tuesday, 17 September 2002 22:29:11 GMT

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