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RE: Problem with auto-generated fragment IDs for graph names

From: Markus Lanthaler <markus.lanthaler@gmx.net>
Date: Mon, 18 Feb 2013 17:58:03 +0100
To: "'Andy Seaborne'" <andy.seaborne@epimorphics.com>, <public-linked-json@w3.org>, "'RDF-WG'" <public-rdf-wg@w3.org>
Message-ID: <011b01ce0df9$1ef6c670$5ce45350$@lanthaler@gmx.net>
On Monday, February 18, 2013 5:17 PM, Andy Seaborne wrote:
> _:0x1234 {
>       x:assertions x:expressedAs x:triples .
>     }
> 
> is a labelling of a graph (value).
> 
> So there is some relationship (not here defined) to the graph and that
> is in the dataset structure.  In your previous message you talked about
> "navigate" and "bnode identifiers".  I understood your description as
> structural navigation of a datastructure from parsing.  Was that right?

Yes.


> You get would get from  _:0x1234 to the graph by looking in the dataset
> structure (which is a map) if bnodes were allowed.  At this level, of
> concrete graph structures, bnode label or a IRI string would serve the
> same purpose using e.g. relative URIs (and a per-parse random base URI
> making it only findable locally).  It's a local structural identifier.

Yes. Would that also be the case if bNodes would *not* denote the graph they
label? As I understand it, if bNodes wouldn't denote the graph, you couldn't
look up a graph labeled with a bNode ID in a dataset because you wouldn't
know if that bNode ID denotes that graph or not. Is that correct?

If you have the following dataset:

{
  _:b1 x:signature "... signature ..." .
}
_:b1 {
  ... some triples ...
}

Do the two _:b1 above refer to the same, i.e., the named graph? Does this
mean that "... signature ..." is the signature of the graph labeled with
_:b1? Or could it be that the signature is about something completely
different?

RDF-CONCEPTS says:

   Despite the use of the word "name" in "named graph", the
   graph name does not formally denote the graph. It is merely
   syntactically paired with the graph. RDF does not place
   any formal restrictions on what resource the graph name may
   denote, nor on the relationship between that resource and the
   graph.

I read this as in the example above you wouldn't know to what the signature
applies. It may or may not be the graph. Manu's use case requires that it is
the graph to which the signature applies. That's the reason why I argued for
"bNodes MUST denote the graph".


Thanks,
Markus


--
Markus Lanthaler
@markuslanthaler
Received on Monday, 18 February 2013 16:58:42 GMT

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