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Re: Questions about Feature Synopsis for OWL Lite and OWL

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Wed, 14 Aug 2002 15:36:50 +0100
Message-ID: <15706.27394.795433.271994@merlin.oaklands.net>
To: Frank van Harmelen <Frank.van.Harmelen@cs.vu.nl>
Cc: "Lacy . Lee" <LLacy@drc.com>, public-webont-comments@w3.org

On August 14, Frank van Harmelen writes:
> 
> 
> Lacy Lee wrote:
> 
> > There is a reference to the predefined class "Nothing" in the section on
> > complex classes (right before section 5).  Are "Thing" and "Nothing" part of
> > Full OWL as opposed to OWL Lite?
> 
> Thing is in OWL Lite, Nothing is only in Full OWL.
> This is also consistent with what the abstract syntax says ([1], just before 
> section 4), but I agree that the Feature Spec could give the matter more 
> emphasis.
> (the justification is probably that the presence of Nothing allows one to 
> encode much more expressiveness than we would want to allow in OWL Lite)

In fact it is trivial to add Nothing to an OWL Lite ontology, e.g., by
asserting:

 subClassOf(Nothing,minCardinality(P,1))
 subClassOf(Nothing,maxCardinality(P,0))

for some property P.

For this reason I consider that leaving Nothing out of Lite was a
simple error.

Ian

> 
> > Also, are "ObjectProperty" and "DatatypeProperty" part of OWL Lite or Full
> > OWL?
> 
> Yes, the Feature Spec delegates this issue to the Abstract Syntax doc [1],
> which (fortunately) is clearer on this.
> They are both part of OWL Lite in a restricted form (see [2]),
> with a more general form in Full OWL:
> 
> "OWL property axioms generalize OWL Lite property axioms by allowing
>  descriptions in place of classes and data ranges in place of datatypes in
>  domains and ranges."
> (from [3])
> 
> Hope this answers your questions,
> both are good pointers for us to improve the document.
> 
> Thanks,
> 
> Frank.van.Harmelen@cs.vu.nl              http://www.cs.vu.nl/~frankh
> Department of AI, Faculty of Sciences,  Vrije Universiteit Amsterdam
> de Boelelaan 1081a, 1081HV Amsterdam, The Netherlands
> tel (+31)-20-444 7731/7700 fax (+31)-84-221 4294
> 
> [1] http://www.w3.org/TR/owl-absyn/
> [2] http://www.w3.org/TR/owl-absyn/#5.1.3
> [3] http://www.w3.org/TR/owl-absyn/#5.2.4
> 
Received on Wednesday, 14 August 2002 10:39:12 GMT

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