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RE: UFDTF Metamodeling Document

From: Conrad Bock <conrad.bock@nist.gov>
Date: Wed, 28 Nov 2007 11:45:13 -0500
To: "'Peter F. Patel-Schneider'" <pfps@research.bell-labs.com>
Cc: <public-owl-wg@w3.org>
Message-ID: <120901c831de$0c39e280$b3200681@MEL.NIST.GOV>

Peter, 

 > > - I would expect the draft metamodel document
 >  >     (http://www.w3.org/2007/OWL/wiki/MOF-Based_Metamodel) is part
 >  >     of the user-facing documents, at a similar level and audience
 >  >     as the reference manual.  It's important that this and the
 >  >     OMG's Ontology Definition Metamodel for OWL are aligned,
 >  >     because OMG is perceived as the primary source for MOF-based
 >  >     metamodels.

 >  Is where any particular reason to make the metamodel document a
 >  recommendation track document?  

It would be fine with me if it weren't, because it would reduce
cross-talk with OMG.  Not sure what Elisa and Evan think.  I
misunderstood which draft documents were on the recommendation track.
BTW, I assume draft documents that are not never included in the
recommedation track will just remain unofficial work of the WG?

 >  Also, the document doesn't appear to have a pointer ot the actual
 >  mdetamodel itself.

Not sure why the authors didn't include the one at
http://www.webont.org/owl/1.1/metamodel.html.

 >  >     Even with no metamodeling, the use of a name as an instance of
 >  >     owl:class and as the type for an individual are of course
 >  >     related.  For example, if M1:car is an instance of owl:Class,
 >  >     it is also the type for M0:johns-car.  This is also true for
 >  >     metamodeling, see next.

 >  I don't understand this in an OWL 1.1 context.  In the functional
 >  syntax for OWL 1.1 there is no owl:class.

Was referring to what I thought would be in the XML interchange format,
which some users would be looking at, see OWL 1 example [1] in
http://www.w3.org/2007/OWL/wiki/OWLMetamodeling.  I'm assuming OWL 1.1
will be backward compatible enough to support that sort of syntax.

 >  If by M1:car you are referring to some MOF or OMG constructs and not
 >  some IRI, then please include a pointer to some place that provides
 >  an understanding of what these constructs mean.

I meant that in the OWL 1 sense (namespace:name).  See example above.

 > > - Finally, we should address a common use of metamodeling that
 >  >     extends OWL for modeling languages.  This defines subclasses
 >  >     of owl:Class with additional properties that have values on
 >  >     the instances of the subclass.  For example, uml:Class as a
 >  >     subtype owl:Class would add characteristics of classes
 >  >     peculiar to UML, such as isAbstract.  This does not imply any
 >  >     DL reasoning on owl:class its subtypes (these are only used to
 >  >     type instances, which are only created, read/queried,
 >  >     modified, and deleted), or introduce any constraints that
 >  >     would affect DL reasoning on the instances of instances of
 >  >     owl:class.

 >  How would these extensions work in OWL 1.1?  

That's my question.  :)  They work in OWL 1, including reasoners (see
example above), so I was expecting OWL 1.1 would be backward compatible
in this.

 > How could it be guaranteed that there are no effects to the DL
 > reasoning paradigm?

If the modeler subclasses owl:Class or owl:Property in a way that
affects DL reasoners, then they're in OWL Full.  We can't make
guarantees when we can't control the modeler.  However, the applications
I'm aware of would be introducing properties or restrictions in
subclasses that would either

  - not affect DL reasoning, or

  - affect it in a way that can be expressed in DL (eg,
    uml:class.isAbstract is equivalent to making the class equivalent to
    union of its subclasses), or

  - the affect would be unspecified and not accounted for by DL
    reasoners.

 >  (I can see at least one way of setting up this sort of thing in OWL
 >  1.1, but I don't know whether it would suit this usage because I
 >  don't know what is supposed to happen.)

Would be very interested to hear about it.

Conrad
Received on Wednesday, 28 November 2007 16:45:48 GMT

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