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Re: SPARQL results in RDF

From: Jerven Bolleman <jerven.bolleman@isb-sib.ch>
Date: Sun, 22 Sep 2013 00:32:51 +0200
Cc: William Waites <ww@styx.org>, "public-lod@w3.org community" <public-lod@w3.org>
Message-Id: <FF3E3054-FCBD-4FDA-8E6A-10EDA589E009@isb-sib.ch>
To: Hugh Glaser <hg@ecs.soton.ac.uk>
Hi Hugh,

I think you disregarded the CONSTRUCT queries a bit to quickly. This is what you use when you want to get back triples.
If you want back result columns you use SELECT. If you want describe to the concept of result columns in RDF then you are
on your own.

Maybe if you explain what you want to represent then we can have a bit more of an informed discussion.

On Sep 21, 2013, at 8:38 PM, Hugh Glaser <hg@ecs.soton.ac.uk> wrote:

> Many thanks, William, and for confirming so quickly.
> (And especially thanks for not telling me that CONSTRUCT does what I want!)
> I had suddenly got excited that RDF might actually be useable to represent something I wanted to represent, just like we tell other people :-)
> So it is all non-standard, as I suspected.
> Ah well, I'll go back to trying to work with XML stuff, instead of using my usual RDF tools :-(
> Very best
> Hugh
> On 21 Sep 2013, at 19:14, William Waites <ww@styx.org>
> wrote:
>> Hi Hugh,
>> You can get results in RDF if you use CONSTRUCT -- which is basically
>> a special case of SELECT that returns 3-tuples and uses set semantics
>> (does not allow duplicates), but I imagine that you are aware of this.
>> Returning RDF for SELECT where the result set consists in n-tuples
>> where n != 3 is difficult because there is no direct way to represent
>> it. 
>> Also problematic is that there *is* a concept of order in SPARQL query
>> results while there is not with RDF.
>> Also the use of bag semantics allowing duplicates which also does not
>> really work with RDF.
>> These, again, could be kludged with reification, but that is not very
>> elegant. 
>> So most SELECT results are not directly representable in RDF.
>> Cheers,
>> -w

Jerven Bolleman                        Jerven.Bolleman@isb-sib.ch
SIB Swiss Institute of Bioinformatics      Tel: +41 (0)22 379 58 85
CMU, rue Michel Servet 1               Fax: +41 (0)22 379 58 58
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Received on Saturday, 21 September 2013 22:34:32 UTC

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