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Re: Negation decision : unexpected effects

From: Steve Harris <steve.harris@garlik.com>
Date: Sat, 3 Apr 2010 08:45:10 +0100
Cc: SPARQL Working Group <public-rdf-dawg@w3.org>
Message-Id: <82E370D2-4495-4204-8B07-9AEBEAE48E44@garlik.com>
To: Andy Seaborne <andy.seaborne@talis.com>
On 2010-04-02, at 22:05, Andy Seaborne wrote:
> The FILTER could be artificially forced using a extra {}
> 
> { { ?s rdf:type :T
>    FILTER NOT EXISTS { ?s :p ?v . }
>   }
>    ?s :q ?v
> }
> 
> This is unnecessary - the more direct syntax is closer to the OPTIONAL/!BOUND idiom that I think it the important thing to make easier.

!BOUND can only be used inside a FILTER as well (though OPTIONAL is not mobile) and users must be used to this, so I'm not sure this is a significant problem.

The main reason I thought the compromise that was found at F2F3 was good was that it made it clear that NOT EXISTS was executed per solution, like a FILTER, and not as an algebraic operator.

- Steve

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Received on Saturday, 3 April 2010 07:45:40 GMT

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