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Re: ACTION-203 done (resolution of ISSUE-118 - semantics of anonymous individuals)

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Thu, 28 Aug 2008 10:51:19 +0100
Message-Id: <3C788858-0339-4937-8AEB-AFEC086A391E@cs.man.ac.uk>
Cc: "Boris Motik" <boris.motik@comlab.ox.ac.uk>, "'W3C OWL Working Group'" <public-owl-wg@w3.org>
To: Alan Ruttenberg <alanruttenberg@gmail.com>

On 28 Aug 2008, at 09:49, Alan Ruttenberg wrote:

> On Aug 28, 2008, at 10:26 AM, Boris Motik wrote:
>
>> Hello,
>>
>> They could; however, the existing way of handling things is  
>> deliberate, as it makes the structural specification more uniform.
>
> Uniform in what way? I would think that having global restrictions  
> be truly global would be a clearer benefit if sensibility of the  
> spec is a desirable.
>
>> Furthermore, as already discussed, there is no observable  
>> difference between the Skolem semantics and the existential one  
>> for all
>> inference problems apart from certain entailments, which DL users  
>> are typically not interested in anyway. In such cases, without
>> changing the set of "interesting" consequences, one can skolemize  
>> the anonymous individuals; but then, one can freely drop the
>> global restrictions altogether without funning into decidability  
>> problems. The way resolution of ISSUE-118 has been implemented
>> allows precisely for that: a tool can simply forget about Global  
>> Restrictions 4 and 5 and obtain a language that can be interpreted
>> under the Skolem semantics for all practical intents and purposes.
>
> Yes, but what language would that be? Why would we want to enable  
> that? Skolem semantics isn't an option we support in any of our  
> profiles.

We need it for 1) SPARQL/OWL and 2) for closer alignment with  
existing RDF and OWL implementation behavior.

Indeed, although I'm  not happy with this outcome (since I believe  
skolemesque semantics are the right one) I'm more comfortable with it  
when presented in this way.

Cheers,
Bijan.
Received on Thursday, 28 August 2008 09:48:50 GMT

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