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Re: Definition: Group in query editor's draft

From: Steve Harris <steve.harris@garlik.com>
Date: Mon, 27 Sep 2010 15:53:06 +0100
Cc: Andy Seaborne <andy.seaborne@epimorphics.com>, Axel Polleres <axel.polleres@deri.org>, SPARQL Working Group <public-rdf-dawg@w3.org>
Message-Id: <7FA50934-1BF4-4B10-BBA7-2B608A67F545@garlik.com>
To: Lee Feigenbaum <lee@thefigtrees.net>
On 2010-09-27, at 13:54, Lee Feigenbaum wrote:

> On 9/27/2010 8:20 AM, Steve Harris wrote:
>> 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.
> 
> Maybe it would be clearer if you used one of these guys?
> 
> http://unicodesnowmanforyou.com/

Heh, I considered introducing another symbol, but SPARQL has it's fair share already.

- Steve

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Received on Monday, 27 September 2010 14:54:17 GMT

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