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

From: Jeremy Carroll <jjc@hpl.hp.com>
Date: Tue, 11 Dec 2007 10:06:14 +0000
Message-ID: <475E6116.7070701@hpl.hp.com>
To: Alan Ruttenberg <alanruttenberg@gmail.com>
CC: Michael Schneider <schneid@fzi.de>, 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

Alan,

if Michael is wrong in the way that you suggest, it should be possible 
to construct a very small counter-example illustrating his mistake.

I believe that the text you give purports to be a recipe for this 
counter-example; but I take your recipe book into my kitchen, and I end 
up spilling my triples on the floor.

So would you mind baking the example for me,

Ahhh - I should clearly state the properties this example would have - 
but I'm not going to manage that today

thanks

Jeremy



Alan Ruttenberg wrote:
> 
> 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 10:06:48 GMT

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