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Re: 4 MINUS and NOT EXISTS test cases

From: Chimezie Ogbuji <ogbujic@ccf.org>
Date: Mon, 19 Jul 2010 12:59:19 -0400
To: "Andy Seaborne" <andy.seaborne@talis.com>
cc: "SPARQL Working Group WG" <public-rdf-dawg@w3.org>
Message-ID: <C869FCA7.1278C%ogbujic@ccf.org>
I've committed these tests into the CVS (all but the last one, which I
cannot reconcile with the behavior of Minus - see below):

RCS file: 
/w3ccvs/WWW/2009/sparql/docs/tests/data-sparql11/negation/manifest.ttl,v
Working file: manifest.ttl
head: 1.1
branch:
locks: strict
access list:
symbolic names:
keyword substitution: kv
total revisions: 1;    selected revisions: 1
description:
----------------------------
revision 1.1
date: 2010/07/19 16:38:23;  author: cogbuji;  state: Exp;

On 7/5/10 5:49 PM, "Andy Seaborne" <andy.seaborne@talis.com> wrote:
> ..snip ..
> I don't agree with this.
> The matching part of the MINUS is:
> { ?otherExam a ex:PhysicalExamination; dc:date ?otherExDT } gives:
> and then the FILTER:
> FILTER(?date<  ?otherExDT&&  ?otherExDT<  ?opDT)
> uses ?date which is out of scope for the clause MINUS so the FILTER is
> error always so nothing matches for MINUS {}

Hmm, I've been staring at this test for a while and cannot determine an
alternative.  This query is meant to implement an exclusion criteria that
rules out the possibility that there is a physical examination that is
closer to the operation (based on lexical ordering of the associated dates),
so any resulting ?exam binding should be the 'closest' examination prior to
the operation.  

However, in order to use the MINUS operator in the same way the EXIST
operator was used in the previous test, I would essentially need to use
?exam as the join condition between the LHS and RHS.  It doesn't seem
possible to use it for this kind of problem since the Minus algebra operator
is defined such that the operands are independent of each other:

Minus(Ω1, Ω2) 
= { μ | μ in Ω1?
    such that for all μ' in Ω2, either μ and μ' are not compatible or dom(μ)
and dom(μ') are disjoint }

Am I missing something?

I have left this particular test out.

-- Chime


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Received on Monday, 19 July 2010 17:00:03 GMT

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