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Re: SPARQL results in RDF

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Sat, 21 Sep 2013 16:12:17 -0400
Message-ID: <523DFDA1.8070800@openlinksw.com>
To: public-lod@w3.org
On 9/21/13 2:38 PM, Hugh Glaser 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

Hugh,

There's nothing wrong with expecting an RDF based description of a 
SPARQL query result. It's something that should have been part of the 
deal, that's why we implemented it in Virtuoso.

Kingsley
>
> 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
>>
>
>


-- 

Regards,

Kingsley Idehen	
Founder & CEO
OpenLink Software
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Received on Saturday, 21 September 2013 20:12:39 UTC

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