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Re: SPARQL results in RDF

From: Hugh Glaser <hg@ecs.soton.ac.uk>
Date: Sat, 21 Sep 2013 23:29:50 +0000
To: Jerven Bolleman <jerven.bolleman@isb-sib.ch>
CC: William Waites <ww@styx.org>, "public-lod@w3.org community" <public-lod@w3.org>
Message-ID: <5D877D3C-BB6F-4799-8500-508D22E87F33@soton.ac.uk>
Thanks Jerven, you may well be right!
SELECT DISTINCT * WHERE
{ ?s foo:bar ?o }
would do.
And things like
SELECT DISTINCT * WHERE
{ ?v1 foo:bar ?o . ?v1 ?p1 ?v2 . ?v2 ?p2 ?v3 }
and then probably get back an identifier for each result, so that I can find out what are the values of the ?p* and ?v*
I think essentially the sort of thing that dbpedia/virtuoso is giving me.
(By the way, Kingsley, replying to this has caused me to notice that the rdfxml does not rapper very nicely - sorry to report!
rapper: Error - URI file:///home/hg/sparql.rdf:8 - property element 'solution' has multiple object node elements, skipping.)

Best
Hugh

On 21 Sep 2013, at 23:32, Jerven Bolleman <jerven.bolleman@isb-sib.ch>
 wrote:

> 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.
> 
> Regards,
> Jerven
> 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
>>> 
>> 
>> 
> 
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> SIB Swiss Institute of Bioinformatics      Tel: +41 (0)22 379 58 85
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Received on Saturday, 21 September 2013 23:30:26 UTC

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