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Re: Negation decision : unexpected effects

From: Lee Feigenbaum <lee@thefigtrees.net>
Date: Mon, 05 Apr 2010 19:20:28 -0400
Message-ID: <4BBA703C.7080107@thefigtrees.net>
To: Paul Gearon <gearon@ieee.org>
CC: Andy Seaborne <andy.seaborne@talis.com>, SPARQL Working Group <public-rdf-dawg@w3.org>
On 4/5/2010 5:56 PM, Paul Gearon wrote:
> On Mon, Apr 5, 2010 at 5:14 PM, Andy Seaborne<andy.seaborne@talis.com>  wrote:
> <snip/>
>> For example:
>>
>> { ?s ?p ?o MINUS { SELECT (:s AS ?s){} } }
>>
>> removes the ?s=:s binding rows regardless of the contents of the graph.
>>
>> { ?s ?p ?o MINUS { ?x ?y ?z } }
>>
>> where the contents of the graph don't matter for the MINUS (if it's empty ?s
>> ?p ?o is zero rows)
>
> Sorry, I'm not clear on this. Are you saying that this just returns
> the contents of the graph, and that the MINUS has no effect since
> there are no matching variables?

Yes, I'm pretty sure that is what Andy is saying. (And that's what the 
extra condition on the MINUS definition ensures.)

Lee
Received on Monday, 5 April 2010 23:21:08 GMT

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