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Re: SPARQL Update 1.1 review part1

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Tue, 08 Feb 2011 09:58:44 -0500
Message-ID: <4D515A24.4090705@thefigtrees.net>
To: Paul Gearon <gearon@ieee.org>
CC: Axel Polleres <axel.polleres@deri.org>, SPARQL Working Group <public-rdf-dawg@w3.org>, Alexandre Passant <Alexandre.Passant@deri.org>
On 2/7/2011 10:38 PM, Paul Gearon wrote:
> Alex originally dealt with Axe's review, but I am going over it now.
>
> I have a question about Axel's point 27:
>
>
> On Thu, Sep 30, 2010 at 6:10 PM, Axel Polleres<axel.polleres@deri.org>  wrote:
>> 27)
>> "Using a new blank node in a delete template will lead to nothing being deleted, as the new blank node cannot match anything that already exists."
>>
>> this seems to contradict resolution http://www.w3.org/2009/sparql/meeting/2010-03-09#resolution_2
>> I haven't seen any resolution overriding that, but I might have missed that. Even if we decided to override that resolution, it is not entirely clear to me what "new" blank node means exactly here.
>
> Here is a copy of the resolution that Alex mentions:
>
> "Blank nodes in DELETE templates act as "wild cards", effectively as
> variables bound to all RDF terms; the same blank node cannot be used
> in the WHERE clause and the template, or in multiple BGPs"
>
> Unfortunately, I was not at this meeting, and it's something that I
> missed when the minutes came around. I find this to be an unfortunate
> decision, as it effectively makes the template part of the WHERE
> clause. To illustrate, the operation:
>
> DELETE { [] :p ?x }
> WHERE { ?x :q :z }
>
> Is going to be effectively the same as:
>
> DELETE { ?a :p ?x }
> WHERE { ?x :q :z . ?a ?p ?o }

Right, this was the goal of the resolution. Can you explain your concern?

> (ignoring the existence of the ?p and ?o)
>
> I'm really uncomfortable with this. Is it set in stone?

Like all decisions, we can revisit it if there is new information that 
was not originally considered, but the later we get in the process, the 
higher the bar for substantive new information to cause us to change a 
decision should probably be.

Lee


> Regards,
> Paul Gearon
>
>
Received on Tuesday, 8 February 2011 14:59:21 GMT

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