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Re: definition of "potentially bound" variable

From: Andy Seaborne <andy.seaborne@epimorphics.com>
Date: Tue, 14 Sep 2010 12:01:30 +0100
Message-ID: <4C8F560A.3050707@epimorphics.com>
To: Axel Polleres <axel.polleres@deri.org>
CC: SPARQL Working Group <public-rdf-dawg@w3.org>


On 14/09/10 11:15, Axel Polleres wrote:

>> The other definitions need to work with GROUP BY which hides the non-key
>> variables variables.  To do this, it would seem easier to define the
>> concept recursively, not declaratively.
>
> my idea was to define it recusrively over the syntax

No problem with that but that's not how the syntax works e.g. OPTIONAL 
isn't a binary operator, it's a syntax element that appears in a group. 
  It's the translation to the algebra and LeftJoin that makes it a 
binary operator.

The definition for "potentially bound" needs to mention a "group" (the 
thing between {}) and accumulate the bound variables through the syntax 
elements that appear in a group.

	Andy
Received on Tuesday, 14 September 2010 11:02:06 GMT

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