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LANG?/SEM?: using resources (was Re: LANG: owl:ontology)

From: Peter F. Patel-Schneider <pfps@research.bell-labs.com>
Date: Wed, 18 Sep 2002 10:40:51 -0400 (EDT)
Message-Id: <20020918.104051.93644536.pfps@research.bell-labs.com>
To: welty@us.ibm.com
Cc: www-webont-wg@w3.org

As far as I can see, there are several ``strange attractors'' in this
space:

Attractor 1:  Resources have definitions.

Attractor 2:  Whenever a resource is used, the intent of the ``definer'' of
  that symbol is automatically a consequence of that use, whether that
  intent is in the form of a definition or even in some other form.

These two seem to be attractive at first glance, but have untenable
consequences in both the RDF and OWL world view.

Attractor 1 has a technical problem.  There is no reasonable way in RDF to
separate out the triples that could form the definition of a symbol, even
if one might argue that the symbol has a definition.  Similarly, OWL has no
notion of what would make up the definition of a class, a property, or an
individual.  I don't see any tenable way of adding the notion of a
definition to OWL, particularly OWL written in RDF.

Because resources can't have definitions in RDF or OWL, Attractor 2 can't
use the notion of a resource.  However, even if there was a way of
selecting the definition of a resource, automatically having the
definition of a resource being a consequence of the use of the resource is
a bad idea.

For example, suppose I want to be able to mention the Taliban in an OWL
ontology.  I have to pick a well-known resource that is commonly used to
refer to the Taliban.  If Attractor 2 is in force, as soon as I do so, I am
committed to whatever the definition of that resource is.  In the case of
the Taliban, I would be forced to choose among the various definitions of
the Taliban, most of which would force rather strong consequences.  The
situation would be even worse if I wanted to related the various
definitions, as I would end up with a contradition just by making a
co-reference between the various definition.

The situation is even worse with Attractor 2 in the absence of
definitions.   To get the intent of the definer of the resource, I would
have to commit to an entire document (or ontology, if you prefer).  Here I
would end up with things like committing to the invasion of Iraq just by
mentioning George W. Bush.


As far as I can see the only viable route is to be able to use resources
without committing to anything related to that resource.  To commit to
something in some other ontology/document, use imports.


Peter F. Patel-Schneider
Bell Labs Research
Received on Wednesday, 18 September 2002 10:41:02 GMT

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