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Re: ISSUE-3: REPORTED: Lack of anonymous individuals

From: Bijan Parsia <bparsia@cs.man.ac.uk>
Date: Wed, 28 Nov 2007 10:06:10 +0000
Message-Id: <3A398313-F79A-4E7C-B9C3-2A5202F06E92@cs.man.ac.uk>
Cc: Boris Motik <boris.motik@comlab.ox.ac.uk>, "'Web Ontology Language (OWL) Working Group WG'" <public-owl-wg@w3.org>
To: Ivan Herman <ivan@w3.org>

On Nov 28, 2007, at 9:26 AM, Ivan Herman wrote:

> Hi Bijan,
>
> just for my understanding:
>
> Bijan Parsia wrote:
>>>
>>> - drop anonymous individuals explicitly in OWL 1.1 DL (and  
>>> perhaps say
>>> in some note that such individuals can be dealt with for all
>>> practical intents and purposes by Skolemization), or
>>
>> I find manual Skolemization to be a bit of a non-starter. People
>> migrating from RDF use BNodes rather freely, so I imagine pellet (for
>> example) will always have a mode wherein it treats them as skolem
>> constants. I also imagine that this will be the default setting.
>> Furthermore, that's certainly how I propose to deal with them when
>> querying with SPARQL/OWL.
>
> what you mean is that if I write OWL1.1 DL statements (including, to
> refer to my previous concern, in some some of the simple tractable
> fragment dialect) in, God forbid, RDF/XML and/or Turtle, using
> _syntactically_ blank nodes, then a tool like Pellet would transform
> them on the fly into Skolem, ie, assign some unique URI-s in the
> process?

Assign some unique (relative to the session) identifiers, yes. They  
could be a certain class of URIs, or they could just be strings  
starting with "_:".

The parsing rules would remain the same, e.g., if I load a file that  
contains a nodeID=x and it imports a file containing a nodeID=x, I  
should get two distinct constants in the graph.

Really, from all user perspectives I've seen, nothing would change  
except that more RDF graphs would be DL legal and the behavior of the  
reasoner would be more familiar, esp. if you worked with RDF  
triplestores and RDFS reasoners before.

> And that is how conformance for tools would be defined for DL
> reasoners?

Yes.

> This would certainly answers a concern I had.

Cool!

Cheers,
Bijan.
Received on Wednesday, 28 November 2007 10:06:19 GMT

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