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ISSUE-91 informal semantics of ontology properties

From: Rinke Hoekstra <hoekstra@uva.nl>
Date: Wed, 2 Jan 2008 20:29:13 +0100
Message-Id: <A0D9BACD-8CD7-45F6-A975-72A879E4ED8A@uva.nl>
To: OWL Working Group WG <public-owl-wg@w3.org>

Hi Boris,

To answer your question about ISSUE-91... you asked what this  
'meaning' or informal semantics of ontology properties in OWL 1.0 is  
that I was referring to. This is actually done in several places.

The owl guide [1] section 6 says:

"Ontology versions may not be compatible with each other. For example,  
a prior version of an ontology may contain statements that contradict  
the current version. Within an owl:Ontology element, we use the tags  
owl:backwardCompatibleWith and owl:incompatibleWith to indicate  
compatibility or the lack thereof with previous ontology versions. If  
owl:backwardCompatibleWith is not declared, then compatibility should  
not be assumed. "

... especially the last comes across as rather normative.

Also section 7.4.3 in the reference [2]

"An owl:backwardCompatibleWith statement contains a reference to  
another ontology. This identifies the specified ontology as a prior  
version of the containing ontology, and further indicates that it is  
backward compatible with it. In particular, this indicates that all  
identifiers from the previous version have the same intended  
interpretations in the new version. Thus, it is a hint to document  
authors that they can safely change their documents to commit to the  
new version (by simply updating namespace declarations and owl:imports  
statements to refer to the URL of the new version). If  
owl:backwardCompatibleWith is not declared for two versions, then  
compatibility should not be assumed.

owl:backwardCompatibleWith has no meaning in the model theoretic  
semantics other than that given by the RDF(S) model theory."

Although this bit states that the ontology property has no 'meaning'  
in the model theoretic semantics, there clearly is an intended  
interpretation. By the way, the RDF(S) model theory requires the range  
of the property to be an owl:Ontology, something that will make  
Pellet, and other systems (eg. the OWL Validator) to conclude that an  
OWL DL ontology is in OWL Full if it does not contain the the type of  
the resource explicitly (P4 simply adds this without complaining). See  
the wiki page on versions [3].

I'm really not saying that we should introduce formal semantics for  
these properties, but we should be careful in throwing away (or  
rather, not mentioning) language elements from 1.0 without documenting  
such a decision. And they do have meaning in the RDF-sense.



[1] http://www.w3.org/TR/owl-guide/
[2] http://www.w3.org/TR/owl-ref/#backwardCompatibleWith-def
[3] http://www.w3.org/2007/OWL/wiki/Ontology_Versions
Drs. Rinke Hoekstra

Email: hoekstra@uva.nl    Skype:  rinkehoekstra
Phone: +31-20-5253499     Fax:   +31-20-5253495
Web:   http://www.leibnizcenter.org/users/rinke

Leibniz Center for Law,          Faculty of Law
University of Amsterdam,            PO Box 1030
1000 BA  Amsterdam,             The Netherlands
Received on Wednesday, 2 January 2008 19:29:20 UTC

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