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Re: Definition: Group in query editor's draft

From: Steve Harris <steve.harris@garlik.com>
Date: Mon, 27 Sep 2010 13:20:54 +0100
Cc: Axel Polleres <axel.polleres@deri.org>, SPARQL Working Group <public-rdf-dawg@w3.org>
Message-Id: <60BF8F5A-02F9-42D2-9D7B-E543174AAC86@garlik.com>
To: Andy Seaborne <andy.seaborne@epimorphics.com>
On 2010-09-23, at 08:36, Andy Seaborne wrote:

> 
> 
> On 22/09/10 06:59, Axel Polleres wrote:
>> I have a small question about the Definition of "Group" in the query draft:
>> 
>> "Group((),&Omega;) = { 1 ->  &Omega; }"
>> 
>> ... shouldn't that be:
>> 
>> "Group((),&Omega;) = { () ->  &Omega; }"
>> 
>> i.e., what is the 1 supposed to mean?
> 
> The 1 is any key.  When the set of groups keys is the empty, which happnes for
> 
> SELECT (count(*) AS ?c) { ?s ?p ?o }
> 
> then there needs to be a key value for the group.
> 
> It could be said to be slightly more sense to be (1), not 1, as it's a list when then the key isn't empty.  The key just needs to be unique, and here, there is only one key so it's arbitrary.

Yeah, I went for a non-list value so there was no possibility of it being the same as a "real" key, but it's perhaps not as clear as it should be.

- Steve

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Received on Monday, 27 September 2010 12:21:29 GMT

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