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RE: "in-scope" and BIND question

From: Polleres, Axel <axel.polleres@siemens.com>
Date: Thu, 10 May 2012 11:44:08 +0200
To: Andy Seaborne <andy.seaborne@epimorphics.com>, "public-rdf-dawg@w3.org" <public-rdf-dawg@w3.org>
Message-ID: <9DA51FFE5E84464082D7A089342DEEE80139B024F293@ATVIES9917WMSX.ww300.siemens.net>
> Do you have suggestions? (I note the definition is based on your
> suggestions)

Right, but that pre-dated BIND, AFAIR... Anyways, I will think of something. 
In principle, I ask myself, why we have to restrict the use of variables assigned to 
in BIND *at all* except for not using variables within the expression on the LHS of the "AS".

> Maybe something needed for across a group?

Hmm, it seems to me that the current clause 12. in the grammar restrcitions 
tries to prohibit something like this:

{
 BIND ( ?X1 AS ?Y)
 BIND ( ?X2 AS ?Y)
}

right? But I am not sure about whether we also want to prohibit this one:

{
 BIND ( ?X1 AS ?Y)
}
{
 BIND ( ?X2 AS ?Y)
}

Anyways, I'll try to check through the "history" again and re-think.

Best,
Axel


> -----Original Message-----
> From: Andy Seaborne [mailto:andy.seaborne@epimorphics.com] 
> Sent: Thursday, 10 May 2012 11:07 AM
> To: public-rdf-dawg@w3.org
> Subject: Re: "in-scope" and BIND question
> 
> 
> 
> On 09/05/12 15:27, Polleres, Axel wrote:
> > I havea a question on in-scope variables and BIND, particularly, on 
> > item 12. in 
> > http://www.w3.org/2009/sparql/docs/query-1.1/rq25.xml#sparqlGrammar
> > # " The variable assigned in a |BIND| clause must not be already 
> > in-scope <http://www.w3.org/TR/sparql11-query/#variableScope>.
> > "
> > I am not sure here, what "already" in-scope means. Can we 
> clarify that?
> 
> Do you have suggestions? (I note the definition is based on your
> suggestions)
> 
> > Particularly, when reading the in-scope definition, I am a 
> bit unsure 
> > of what happens with regards to e.g. UNION queries, i.e. my 
> feeling is 
> > that SELECT * { { BIND (1 AS ?Y) } UNION { <s> <p> ?Y } } 
> shouldn't be 
> > different from SELECT * { { <s><p> ?Y } UNION { BIND (1 AS 
> ?Y) } } and 
> > both should be allowed (returning 1 on the empty graph), is that 
> > correct?
> 
> This is legal.  Scope as defined works bottom-up.
> 
> Maybe something needed for across a group?
> 
> 	Andy
> 
> > thanks,
> > Axel
> > --
> > Dr. Axel Polleres
> > Siemens AG Österreich
> > Corporate Technology Central Eastern Europe Research & 
> Technologies CT 
> > T CEE
> > Tel.: +43 (0) 51707-36983
> > Mobile: +43 (0) 664 88550859
> > Fax: +43 (0) 51707-56682 mailto:axel.polleres@siemens.com
> 
> 
Received on Thursday, 10 May 2012 09:44:43 GMT

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