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Re: [Turtle] Two formats

From: Steve Harris <steve.harris@garlik.com>
Date: Thu, 3 Mar 2011 21:53:35 +0000
Cc: Richard Cyganiak <richard@cyganiak.de>, Sandro Hawke <sandro@w3.org>, nathan@webr3.org, RDF-WG <public-rdf-wg@w3.org>
Message-Id: <E06A0F2A-50F5-4107-B7A9-705379FFB7C9@garlik.com>
To: Andy Seaborne <andy.seaborne@epimorphics.com>
On 2011-03-03, at 11:18, Andy Seaborne wrote:
> On 03/03/11 07:51, Steve Harris wrote:
>> Consequently there are several cases where the user would like to
>> have different behaviours depending on whether the file you're
>> parsing has 3 or 4 columns, so lets make it easy to find out without
>> pre-parsing the whole file.
> Does
> N-quads serializes a dataset (default graph and named graphs)
> N-Triples serializes a graph
> work for you?


> It means that in N-Quads, the absence of the 4th column means default graph.  I know 4Store does not have an independent default graph but some other systems do.  N-Quads should capture the generality of an RDF dataset or graph store.

FWIW, 4store does have a default graph (now), but internally it has a URI. By default it's just treated like another named graph.

I have a slight reservation about having N-Quads lines with only 3 columns writing to the default graph, it means that "mv foo.nt foo.nq" gives a syntactically legal file, but changes the meaning of the file quite dramatically.

Something more like the following would be my preference:
<http://example.com/a> <http://example.com/a> <http://example.com/a> DEFAULT .

It also ties in to SPARQL 1.1's DROP DEFAULT etc.

- Steve

Steve Harris, CTO, Garlik Limited
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Received on Thursday, 3 March 2011 21:54:12 UTC

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