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Re: RDF-ISSUE-82 (TriG repeated graph iris): How should repeated graph iri labels be handled in TriG [RDF Turtle]

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Wed, 21 Dec 2011 15:50:46 -0500
Message-ID: <4EF246A6.9040107@thefigtrees.net>
To: RDF Working Group WG <public-rdf-wg@w3.org>
CC: RDF Working Group Issue Tracker <sysbot+tracker@w3.org>
On 12/21/2011 12:53 PM, RDF Working Group Issue Tracker wrote:
>
> RDF-ISSUE-82 (TriG repeated graph iris): How should repeated graph iri labels be handled in TriG [RDF Turtle]
>
> http://www.w3.org/2011/rdf-wg/track/issues/82
>
> Raised by: Gavin Carothers
> On product: RDF Turtle
>
> There are a number of ways of handling the case of multiple instances of a graph iri labelling a number graph statements.
>
> Sample TriG Document:
>
> @base<http://example.com/>
> <graph>  {<s>  <p>  <o>  . }
> <graph>  {<s2>  <p>  <o2>  . }
>
> 1) Disallowed (TriG input document behaviour)
>
> "In a TriG document a graph IRI must not be used to label more then one graph."
>
> Result: Parse Error
>
> 2) Merge
>
> "In a TriG document graph statements with the same graph IRI should be merged to form a single RDF Graph."
>
> Result:
> @base<http://example.com/>
> <graph>  {<s>  <p>  <o>  .
>            <s2>  <p>  <o2>  . }
>
> Note: BlankNode labels in each graph statement would either result in shared blank nodes or independent blank nodes (??)

We do merge currently, and we do rely on this in certain places. That 
said, if there was strong sentiment against this behavior, we could live 
with 0 (disallowed) and would switch to N-Quads for true interop and 
probably continue using the merge approach internally.

Lee

>
> 3) Replace
>
> "Upon encountering a graph statement with the same graph IRI of another graph statement, the most recently parsed RDF Graph should replace the earlier one in the RDF Dataset."
>
> Result:
> @base<http://example.com/>
> <graph>  {<s2>  <p>  <o2>  . }
>
> 4) Ignore
>
> "Graph statements with a repeated graph IRI are ignored. Only the first graph statement is added to the RDF Dataset."
>
> Result:
> @base<http://example.com/>
> <graph>  {<s>  <p>  <o>  . }
>
> 5) Document Decides
>
> Apply one of 1-4 on the basis of a directive "@policy". Default to Disallowed.
>
>
>
>
>
>
Received on Wednesday, 21 December 2011 20:51:25 GMT

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