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Re: Mapping to RDF Graphs and reification

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Wed, 3 Dec 2008 17:03:04 +0000
Message-Id: <90D19144-CD6C-4158-A319-8B08537CE094@cs.man.ac.uk>
Cc: public-owl-dev@w3.org
To: Jeff Thompson <jeff@thefirst.org>

On 3 Dec 2008, at 16:49, Jeff Thompson wrote:

> In mapping OWL to RDF graphs, to make an annotation on a triple,  
> the triple
> is reified into separate subject, predicate and object assertions
> similar to reification in RDF.
>
> _:x rdf:type owl:Annotation
> _:x owl:subject T(y)
> _:x owl:predicate T(AP)
> _:x owl:object T(av)
>
> But Tim Berners-Lee is still saying that reification in RDF is broken.

Tim is hardly the only one.

> See this message from last year:
> http://lists.w3.org/Archives/Public/semantic-web/2007Jan/0088.html
>
> If reification in RDF is broken, and OWL adopts the same method for
> quoting a triple so that it can be annotated, does OWL inherit
> the same problems Tim has been talking about for all these years?

Tim's problem is a bit odd as he seems to think that there is a Use/ 
Mention problem with the objects of reification statements. I.e.,  
compare:
	s p o.

and
	_:x owl:subject s.

 From what I can tell, he's objecting to the fact that those "s"s are  
at the same level, i.e., have the same referent (in any model).

Personally, I think this is the least interesting problem with  
reification, if it is a problem at all :)

It's definitely not a problem for the non-Full versions of OWL since  
all this stuff is mere syntax. The way we're using it, we typically  
*want* the s to denote something in the domain, and, in fact, to  
denote the same object.

Consider:
	s p o
	not(s p o)

(where the second is a negated triple). We want these to contradict.  
The latter is serialized using the owl reification vocabulary. So we  
want those ss, ps, and os to be talking about the same thing at the  
same time.

Thus, I don't think that's a problem.

Hope this helps.

Cheers,
Bijan.
Received on Wednesday, 3 December 2008 17:00:05 GMT

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