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Re: Axiom annotations

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Wed, 18 Apr 2007 21:36:57 +0100
Message-Id: <553F39AF-6366-4913-B2ED-0D3D223853D0@cs.man.ac.uk>
Cc: public-owl-dev@w3.org
To: Michael Schneider <m_schnei@gmx.de>

On Apr 18, 2007, at 8:49 PM, Michael Schneider wrote:

> Hi all (especially those working on OWL1.1)!
> Alan Ruttenberg wrote on Tue, 17 Apr 2007:
>>  From http://webont.org/owl/1.1/rdf_mapping.html
>>> Axioms with annotations are reified. If s p o is the RDF   
>>> serialization of the corresponding axiom without annotations  
>>> given  in Table 2 and the axiom contains annotations Annotation 
>>> (apIDi  cti), 1 ? i ? n, then, instead of being serialized as s p  
>>> o, the  axiom is serialized as follows:
>>> _:x rdf:type owl11:Axiom
>>> _:x T(apIDi) T(cti)   1 ? i ? n
>>> _:x rdf:subject s
>>> _:x rdf:predicate p
>>> _:x rdf:object o
> Wouldn't the introduction of RDF reification into the OWL2RDF  
> mapping exclude the reification vocabulary from being used in OWL  
> axioms?

Not necessarily, but it would be consistent with the existing  
rationale. It partly depends on how one handles syntax reflection.

> Just a few days ago, we had an analog discussion for rdf:List and  
> friends here in the "Restrictions on Bags and Seqs content" thread,  
> remember?

I've not finished my message for that, but short answer from me is  
that I think, even for RDF, Bags and Seqs are known to be broken, and  
rdf:List is not a good idea. Historically, I believe rdf:List was  
introduced in order to encode DAML+OIL syntax in the first place.

> Until now, reification hasn't been blacklisted in
>   http://www.w3.org/TR/owl-semantics/mapping.html#4.2
> but then it would probably be.
> Again, yet another widely used feature of RDF which is going to be  
> forbidden in OWL.

Some might take issue with the terms "widely used" and "feature" when  
applied to reification.

> And don't forget those people who would like it to see reification  
> completely removed from the RDF spec:
>   http://lists.w3.org/Archives/Public/semantic-web/2007Jan/0088.html
> I believe with reification deeply embedded in the OWL standard, all  
> hopes of them will be off.

I'd be interested in your use cases. I believe they are used in EARL  
but know of no other systematic use of them.

Frankly, I'm extra loathe to privilege them any more to the extent  
that we do. Fix it, don't enshrine it.

In general, I think one is better off making up one's own reification  
scheme. The interop isn't any worse, and you aren't seduced by the  
"rdf:" into thinking you were doing something special.

> Perhaps, the simplest and most conservative workaround would be to  
> use a "shadow version" of RDF reification, with same vocabulary and  
> semantics, but from a different namespace:
>   owl11:Statement
>   owl11:subject, owl11:predicate, owl11:object

As I'm sure you know, this is a standard move for me, but really it  
could go *either way*. Except for one syntax trick in RDF/XML there  
is *no* standard behavior wrt the reification vocabulary and, afaik,  
little support for doing anything interesting with it in existing  
toolkits (I'm not aware, for example, of any toolkit which maps  
reified triples into  compact form the way e.g, CWM does with the  
list vocabulary).

Received on Wednesday, 18 April 2007 20:37:13 UTC

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