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RDF Core and Dark Triples (from RDF Core)

From: Jim Hendler <hendler@cs.umd.edu>
Date: Thu, 18 Apr 2002 23:40:52 -0400
Message-Id: <p05101515b8e540f37d1b@[10.0.1.3]>
To: webont <www-webont-wg@w3.org>
Brian McBride sent the following message to the RDF Core Working 
Group -- I think it is the best summary of the current status of the 
Dark Triples situation as it stands now - and I quote it in its full, 
instead of pointing via URI, to make it easier for you to read it.
  I particularly want to emphasize the last sentence:

>Before we start forming our judgements, lets get the facts sorted out.

I am hoping the members of our WG who also sit on RDF Core will keep 
us informed about their deliberations, and that those who care about 
the issue will try to find ways to work with each other and to help 
us work out a viable solution to these difficult issues
  -Jim H.


>X-Sender: europe1\bwm@0-mail-1.hpl.hp.com
>Date: Thu, 18 Apr 2002 16:37:38 +0100
>To: RDF Core <w3c-rdfcore-wg@w3.org>
>From: Brian McBride <bwm@hplb.hpl.hp.com>
>Subject: Dark Triples
>X-MailScanner: Found to be clean
>
>Jim Hendler has sent a message [1] to the sw coordingation group which states:
>
>[[
>>
>>If the WebOnt language is to
>>    1/ use RDF syntax, and
>>    2/ be an extension of RDF, and
>>    3/ to be able to entail appropriate class memberships,
>>then the WebOnt language needs to have a facility for having RDF triples
>>that do not denote in the RDF model theory (a.k.a. dark triples) and URI
>>references that do not denote in the RDF model theory (e.g., URI references
>>that only exist in dark triples).
>
>
>The WOWG has reached strong consensus on the above -- we have
>determined that the 3 features above are mandated by our charter, and
>that we cannot have all three unless RDF core does something with
>respect to dark triples (as discussed above) We have several
>volunteers from WebOnt WG who will be willing to engage with RDF Core
>members in resolving this issue to the satisfaction of both groups
>(this includes several people who are in both groups).
>]]
>
>I take that view that we are all in this together and if webont have 
>reached strong consensus on this issue, this is something RDFCore 
>should take seriously.  Consensus is often hard fought and is thus 
>valuable.  I don't think that behaviour that might be construed as 
>confrontational is helpful.
>
>We asked Jeremy to post a motivating example of the problem and at 
>least to the best of my understanding, we have had three different 
>responses:
>
>  Jeremy: students and employees
>  Pat:    no example, denying students and employees
>  Jos:    Peter F. Patel-Schneider's encoding of Russel's paradox in DAML+OIL.
>
>I'm not sure how Pat's description of the problem relates to the PPS 
>paradox - the paradox may be an example of Pat's general description.
>
>I understand that the PPS paradox, as currently formulated, is no 
>longer an issue as some of the constructs used in it have been 
>withdrawn from owl.  I don't know whether that the solves the 
>problem or whether it can be reconstituted in another form.
>
>What is apparent, is there is no consensus on a description of the 
>problem that dark triples will fix and how they will fix it.  So the 
>first step is, I suggest, for the folks who have been involved in 
>the discussion so far to agree at least on that.  I would expect 
>such descriptions to include both an abstract, but accessible 
>description of the problem and at least one concrete example.
>
>Whilst we are aiming for last call is not the most welcome time to 
>receive new issues.  However, I suggest we should work 
>constructively with webont to assess this issue and decide how best 
>to deal with it.  Questions of charter will be for the CG; it may be 
>best to deal with it now, it may be best to handle it in a new spec 
>synchronized with the webont process.  To reach an informed 
>consensus on that question, we all need a clearer understanding of 
>what the problem is, where we are in understanding the possible 
>solutions and how those solutions relate to other issues we have.
>
>Before we start forming our judgements, lets get the facts sorted out.
>
>Brian
>
>[1] http://lists.w3.org/Archives/Member/w3c-semweb-cg/2002Apr/0010.html


-- 
Professor James Hendler				  hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies	  301-405-2696
Maryland Information and Network Dynamics Lab.	  301-405-6707 (Fax)
AV Williams Building, Univ of Maryland		  College Park, MD 20742
http://www.cs.umd.edu/users/hendler
Received on Thursday, 18 April 2002 23:40:58 GMT

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