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Re: [OWLWG-COMMENT] ISSUE-55 (owl:class)

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Mon, 10 Dec 2007 18:23:45 +0000
Message-Id: <A6677D26-5C0B-4600-9BD7-9CAFB10F6ACE@gmail.com>
Cc: "Owl Dev" <public-owl-dev@w3.org>, <hendler@cs.rpi.edu>, <boris.motik@comlab.ox.ac.uk>, <pfps@research.bell-labs.com>, <ian.horrocks@comlab.ox.ac.uk>, <dlm@ksl.stanford.edu>, <hans.teijgeler@quicknet.nl>
To: Michael Schneider <schneid@fzi.de>

Here's my understanding of the situation (if I've got it wrong  
somewhere, please correct me).

On Dec 8, 2007, at 3:20 PM, Michael Schneider wrote:

> But, AFAICS, this would only become a real problem, if in this  
> ontology some class is used as an individual (metamodelling).

Or if the class has instances that are literals.

> But in such a case, even after changing rdfs:Class to owl:Class,  
> the resulting ontology would still be an OWL-Full ontology: There  
> would, for example, be an 'rdf:type' triple with some class being  
> at the individual position, or a class with an object or data property
> attached.

The type triple is inferred in OWL Full - it doesn't have to be  
explicit.

> The OWL-DL reasoner would refuse to work in such a situation, of  
> course.

Because the triple would sometimes need to be inferred by the  
reasoner itself, the DL reasoner can't detect the situation in all  
cases. Strictly speaking, it can only detect the case where it  
certainly shouldn't work.

> So it looks to me that this recommendation is safe.

I would say, no. However it might be ok if the user was warned, or  
made an explicit declaration to that effect.

> Or to summarize these recommendations in a simple rule of thumb:  
> Assume 'rdfs:Class' in RDFS ontologies, assume 'owl:Class' in OWL  
> ontologies.

How do you tell the difference between and RDFS ontology and and OWL  
ontology?

I think what might "work" is commonly called "duck typing", as in, if  
it walks like a duck and quacks like a duck, then....

The application in this case would be to look for an *explicit*  
mention of something that might be only *inferred* in an OWL Full  
ontology. Absent the explicit mention, you might assume that that the  
author did not intend there for such statements to be inferred  
either. This would be a change from the current semantics, and  
possibly a reasonable ones, depending, IMO, on how the OWL Full  
advocates voted.

-Alan
Received on Tuesday, 11 December 2007 00:19:13 GMT

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