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

From: RDF Working Group Issue Tracker <sysbot+tracker@w3.org>
Date: Wed, 21 Dec 2011 17:53:06 +0000
To: public-rdf-wg@w3.org
Message-Id: <E1RdQLi-0006v6-My@tibor.w3.org>

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.
Received on Wednesday, 21 December 2011 17:53:11 GMT

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