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Re: datatypes and MT (#rdfms-graph)

From: Graham Klyne <Graham.Klyne@MIMEsweeper.com>
Date: Fri, 16 Nov 2001 11:37:32 +0000
Message-Id: <5.1.0.14.2.20011116113247.03b39cc0@joy.songbird.com>
To: Pat Hayes <phayes@ai.uwf.edu>
Cc: w3c-rdfcore-wg@w3.org
It's almost a victim of its own beauty ;-)

I completely overlooked the section of graph merging when I responded, 
partly because it was so short but mostly because I wasn't expecting it to 
be in the section on entailment...   (That's not much of an excuse really, 
it is well-enough signposted in the document;  oh well.)

Anyway, a simpler suggestion might be to simply move the definition of 
graph merging up to section 0.2, just after the definition of tidiness?

#g
--

At 04:35 PM 11/15/01 -0600, Pat Hayes wrote:
>>At 09:03 AM 11/15/01 -0600, Dan Connolly wrote:
>>>No? Why not? How is it that you conclude that bnodes
>>>in different graphs are different? I don't see it stated
>>>in the model theory.
>>
>>It appears it's not stated directly, and probably should be since that 
>>was (to me) clearly the intent of our discussions.  Also, the final 
>>sentence of this text from section 2.0 pretty clearly signals that intent:
>>
>>[[[
>>This effectively treats all unlabeled nodes as existentially
>>quantified in the RDF graph in which they occur. Notice that since
>>two nodes cannot have the same label, there is no need to specify
>>the 'scope' of the quantifier within a graph. (However, it
>>is local to the graph.) If we were to apply the semantics
>>directly to N-Triples syntax, we would need to indicate the
>>quantifier scope, since in this lexicalization syntax the same bNode 
>>identifier may occur several times. The above rule amounts to
>>the N-triple convention that would place the quantifiers just
>>outside, i.e. at the outer edge of, the N-triple document
>>corresponding to the graph.
>>]]]
>
>The reason why this issue is treated rather elliptically in the MT is that 
>the great merit of the graph syntax, as I see it, is that the issue simply 
>*does not come up*.  There are no quantifiers, no bound variables and no 
>scopes to keep track of, it all works out automatically. The merging 
>conditions are a joy to state (merge nodes required to be tidy, ie 
>urirefs; don't merge anything else.) It's beautiful. It seemed perverse to 
>introduce the clunky logical notation only to be able to say that we don't 
>have those problems.
>
>If people feel that this issue should be aired more thoroughly, I would 
>suggest that I write a slightly fuller account of how the graph syntax 
>makes local scoping unnecessary, maybe with a couple of examples, and put 
>it into the 'mapping into logic' section, and then refer to that from 
>elsewhere in the document as needed. Any objections/comments?
>
>Pat
>
>--
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Graham Klyne                    MIMEsweeper Group
Strategic Research              <http://www.mimesweeper.com>
<Graham.Klyne@MIMEsweeper.com>
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Received on Friday, 16 November 2001 07:36:33 EST

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