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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: Pat Hayes <phayes@ihmc.us>
Date: Wed, 4 Jan 2012 19:44:57 -0600
Message-Id: <1421950F-686D-4416-969D-19EA8DCADC9B@ihmc.us>
To: RDF Working Group WG <public-rdf-wg@w3.org>
Just on elegance grounds, I would vote for 2, with blank node labels assumed to be shared ( ie do not standardize apart, ie take the simple union of the labeled graphs rather than their merge.) So to state it concisely: 
> "In a TriG document graph statements with the same graph IRI should be unioned to form a single RDF Graph."

Pat

On Dec 21, 2011, at 11:53 AM, 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 (??)
> 
> 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.
> 
> 
> 
> 
> 
> 

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Received on Thursday, 5 January 2012 01:45:28 GMT

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