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Re: reusing URIs vs. mapping with owl:equivalentClass

From: Matthew Pocock <matthew.pocock@ncl.ac.uk>
Date: Fri, 20 Apr 2007 19:27:35 +0100
To: "Kim, Soonho (KCEW)" <Soonho.Kim@fao.org>
Cc: public-owl-dev@w3.org
Message-Id: <200704201927.35165.matthew.pocock@ncl.ac.uk>

On Friday 20 April 2007, Kim, Soonho (KCEW) wrote:
> 	Dear all,
> 	I have two related ontologies. One contains concepts represented in
> multiple languages and with some relationships. The other covers only a
> little part of this ontology, do not have all languages, but extend it with
> many other related concepts. There are concepts that are the same in the
> two ontologies.
> 	Would it be better to reuse the URI of concepts in both ontologies or
> should I assign new URIs to the second (more detailed) ontology and use the
> equivalentClass construct?  What it be better?  For reasoning purposes what
> it is better? How does the current reasoner such as Pellet or Racer process
> owl:equivantClass?

Well, from the point of the owl semantics, asserting that two classes are 
equivalent has the same effect than using the same URI in both. Individuals 
will be classified to the same places in either case. It boils down to what 
you want to communicate to somebody reading the ontology.

If you wish to state that these are the exact same class, then use a single 

If you wish to state that these are two classes (possibly with different 
restrictions, conditions, annotations) but that being an instance of one 
always and for every instance means that you are an instance of the other, 
then use two URIs and an equivalent class axiom.

If what you mean is that you are re-using a class defined in one OWL file in 
another, then as Alan said, consider an import.


> 	Concerning maintenance, the first big ontology may be maintained, the
> second one may be not.
> 	Thank you
> Best Regards,
> Soonho Kim
> Knowledge and Information Consultant
> WAICENT Knowledge Exchange Facilitation Branch (KCEW)
> Knowledge and Communication Department
> Food and Agriculture Organization of the United Nation
> Viale delle Terme di Caracalla
> 00100 Rome, Italy
> Telephone: (+39) 06 5705 3409
> Email: Soonho.Kim@fao.org
Received on Friday, 20 April 2007 18:28:02 UTC

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