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LC Comment: "Hidden" Axioms

From: Bijan Parsia <bparsia@cs.manchester.ac.uk>
Date: Fri, 23 Jan 2009 21:33:02 +0000
Message-Id: <E95D7E5C-BE1E-4381-88D1-32B9A311B82F@cs.manchester.ac.uk>
To: W3C OWL Working Group <public-owl-wg@w3.org>

This is the result of discussions with people at Manchester working on  
a collaboration with Siemens Medical Health Services (i.e., an  
industrial project).

We would like the ability to "turn off" the logical force of axioms  
without having to remove them from the structural model. Currently,  
the only way to directly hide an axiom from a reasoner in an OWL  
document is to use one of the commenting capabilities of the  
serializations (e.g., <!-- -->). However, this isn't really workable  
for a number of reasons including that such comments tend to not  
survive conversion, or even parsing (since it has no place in the  
structural model) and such comments are difficult to retrieve or  
manipulate.

One basic use of this is to maintain superseded (or potentially  
superseded) axioms in the same ontology as the superseding ontology.  
In a sense, this is like deprecatedClass except that it has a clear  
operational meaning (whereas deprecatedClass was unspecified). From an  
API point of view, hiding an axiom (rather than deleting it) is a  
natural way of exploring the consequences of changes. It's nice to be  
able to persist such experiments in the canonical format.

Ideally, in our view, this would be effected by a designated  
"annotation". I've gotten some feedback that this would be an  
exception to the "annotations don't affect the meaning".

True. But I don't think it's a harmful exception *if built in*. For  
obvious reasons it *can't* be conformingly implemented as an extension  
to OWL 2 since all user defined annotations can be deleted without  
changing the logical meaning of the ontology. Keeping it as an  
annotation (rather than a distinct syntactic flag) is both easier to  
spec (since it doesn't change as many documents) and can be combined  
with axiom names to produce multiple external "profiles" of an  
ontology (e.g., by hiding different sets of axioms from different  
external files which import the core ontology). This makes it easier  
to make cut down versions of an ontology from the same source.

I apologize for not raising it earlier. I had been thinking that it  
could all be handled at a higher level. But in order to publish  
ontologies with hidden (in this sense) axioms, it has to be part of  
the core spec. Otherwise, conforming tools will misinterpret such  
ontologies.

Cheers,
Bijan.
Received on Friday, 23 January 2009 21:33:38 GMT

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