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Re: Generic "Graph" Use Cases

From: Richard Cyganiak <richard@cyganiak.de>
Date: Sun, 6 Mar 2011 22:48:39 +0000
Cc: Andy Seaborne <andy.seaborne@epimorphics.com>, RDF Working Group WG <public-rdf-wg@w3.org>
Message-Id: <8F01C960-9162-4BED-83D9-CCCBFAD31270@cyganiak.de>
To: nathan@webr3.org
On 6 Mar 2011, at 21:53, Nathan wrote:
>>>> RDF datasets don't address the assertions about graphs UC very well.
>>>> They can - with careful graph naming (naming the g-snap, not the g-box), the default graph can contain assertions about the properties of a graph, just like graph literals can be used for RDF datasets.  It's just there is "some assemble required".
>>> 
>>> There's a very critical detail here, the need to talk about a g-box, and the need to talk about a g-snap
>> 
>> Just to be sure we're on the same page in this discussion, can you give an example for “talking about a g-box” and one for “talking about a g-snap”, in particular one where the distinction matters?

I'd still be very interested in seeing an example for “talking about a g-box” and one for “talking about a g-snap”, in particular one where the distinction matters.

> Essentially, a large proportion of the use-cases (if not 100%) can be handled with either anonymous-snap or named-snap, the difference between the two is that with anonymous-snap it's all within the RDF data model, where-as with the named-snap approach (example 1 of trig) the names are properties of the serialization,

No, in TriG the graph names are not properties of the serialization. They are properties of the data model (abstract syntax), which is RDF Datasets as defined in SPARQL 1.0.

> and it requires out of band knowledge about the document in order to know what the :Gn's are for / how to piece them together etc.
> 
> To expand on this last comment, if you take examples 1 and 3 from the trig documentation, and replace :G1,:G2,:G3 in the first example for their full URIs, then what do you have here? is it a capture of the current state of three named-box's, or is it three named-snap's to be considered for provenance information? This is what I mean by out of band knowledge.

How is this different in the graph literal approach? It seems to me that you need out-of-band information to answer that question there too, for example in the form of a vocabulary used to make RDF statements about the graph literals. That same approach can be used to transmit such information in the RDF Dataset approach, where it's not clear from context.

> There is a very fun question though, if we did move to a trig like syntax, and one wanted to take a snapshot of a trig doc and talk about it, how would you do it?

I guess you'd put the snapshot at <http://example.com/files/foo_2011-03-06.trig> and talk about that URI.

Do we have use cases in the wiki that require this?

Best,
Richard


> wrap things up in a nother set of curly braces and assign another name? or?
> 
> Will leave it there
> 
> Best,
> 
> Nathan
Received on Sunday, 6 March 2011 22:49:13 UTC

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