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Re: evaluating SPARQL w.r.t an RDF query language survey

From: Jeen Broekstra <jeen@aduna.biz>
Date: Thu, 07 Apr 2005 12:46:35 +0200
Message-ID: <42550F8B.5010301@aduna.biz>
To: public-rdf-dawg@w3.org
Cc: Dan Connolly <connolly@w3.org>

On Apr 6, 2005, at 12:07 AM, Dan Connolly wrote:
> A comment asks...
> "How many of the 14 test questions in [1] does the current SPARQL spec
> cover ?"
>  --
> http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2005Apr/0005.html
>  -> http://www.aifb.uni-karlsruhe.de/WBS/pha/rdf-query/
> I'm interested to take a crack at it, but I'd like some confirmation
> from other WG members that I've got this right before I reply.
> Perhaps it's worth making these into test cases...

I am one of the co-authors of that report, so if I can help out in any 
way let me know.


> 5 Quantification
> Return the persons who are authors of all publications.
> nope.
> The langauges with "yes" in this column seem to
> support closed-world assumptions that
> we don't support in SPARQL.

I'm guessing that you are referring to the FORALL operation used in 
the example RQL query? Or more generally, to the notion of "all 
publications" in the specification of the query?

Is universal quantification by definition something that falls outside 
  SPARQL, or can it be scoped (for example, employing quantification 
on a named graph to allow closed-world assumption on that particular 

> 6 Aggregation
> Count the number of authors of a publication.
> nope.
> unique names assumption.

I have trouble with this. I think that defining a counting operation 
that does not count entities, but simply labels (URIs, bNodes, 
literals), would be useful. This does not make any unique names 
assumption, AFAICS. Counting would simply be a way of retrieving the 
number of results a query would give, without giving the actual result.

Jeen Broekstra          Aduna BV
Knowledge Engineer      Julianaplein 14b, 3817 CS Amersfoort
http://aduna.biz        The Netherlands
tel. +31(0)33 46599877  fax. +31(0)33 46599877
Received on Thursday, 7 April 2005 10:44:47 UTC

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