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Re: Making progress on graphs

From: Pat Hayes <phayes@ihmc.us>
Date: Tue, 22 May 2012 20:06:05 -0500
Cc: Guus Schreiber <guus.schreiber@vu.nl>, RDF Working Group WG <public-rdf-wg@w3.org>
Message-Id: <DE0340E8-AC75-44C9-B086-FD81E99AB3CF@ihmc.us>
To: Richard Cyganiak <richard@cyganiak.de>

On May 22, 2012, at 10:35 AM, Richard Cyganiak wrote:

> On 22 May 2012, at 16:00, Pat Hayes wrote:
>>>>>>> ISSUE-28 Syntactic nesting of g-texts http://www.w3.org/2011/rdf-wg/track/issues/28
>>>>>>> PROPOSED: Close ISSUE-28 ("Do we need syntactic nesting of graphs (g-texts) as in
>>>>>>> N3?"), saying No, we do not -- they are useful, but we can provide the same
>>>>>>> functionality with datasets.
>>>>> 
>>>>> Let's assume the abstract syntax supported nested graphs. Then we can convert that to a “flat” dataset like this: For any nested graph G, replace it by a new IRI i, and add a new pair <i,G> to the dataset.
>>>> 
>>>> I was afraid of that. That works only if we give the datasets a semantics in which the graph 'name' really does denote the named graph, in the 2004 semantics sense of 'denote'.
>>> 
>>> Why? Can you give an example where this does not work?
>> 
>> […T]he 2004 specs say that when an IRI appears in a triple, the truth of the triple depends upon what the IRI *denotes*. So if the IRI denotes something else, or has some other relationship to the graph (or both), then using that IRI inside some RDF isnt going to refer to the named graph at all.
> 
> But I didn't say that I want to refer to a named graph. I want to refer to a resource. That resource is associated in some way with the RDF graph (I'm trying to call this association the “state relationship” or rdf:state, as described in the other ongoing thread).
> 
> So, the pair <i,G> states that the denotation of i is associated with G. Any triples involving i thus refer to the thing associated with G. That's, I believe, all we need to “flatten” a “nested” abstract syntax into an RDF dataset.
> 
> How exactly this association works formally, or if it is formally defined at all, is a valid question, but one that seems orthogonal to ISSUE-28 above.
> 
>> In a nutshell: if you want to use the graph names to refer to the graph, then they must actually refer to the graph. 
> 
> I don't want them to refer to the graph. I want them to refer to a resource that is associated with a graph.

Then the proposed conversion does not work. The IRI will refer to something. That thing will be what is being talked about in the RDF triple using that IRI. If that thing is not the graph, then something is wrong. No, we cannot solve issue-28 now and clean this up later. 

Pat

> 
> Best,
> Richard
> 

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Received on Wednesday, 23 May 2012 01:07:02 GMT

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