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Difference operator in SPARQL

From: Andrew Newman <andrewfnewman@gmail.com>
Date: Sun, 9 Jul 2006 23:12:00 +1000
Message-ID: <2db5a5c40607090612j3de8b4a0ie8f5044256c49976@mail.gmail.com>
To: public-sparql-dev@w3.org

I'm currently searching for reasons why set difference may not have
been included in SPARQL.  The places I have seen it mentioned all seem
to suggest that SPARQL would be incomplete without it [1][2][3].  And
another example works around it using FILTER [4].

I'm looking into this as one of the ways OPTIONAL could have been
implemented would've been a combination of project, join, difference
and union (3 of which are supported in SPARQL directly).

[1] http://www.hpl.hp.com/techreports/2005/HPL-2005-170.pdf
[2] http://www.polleres.net/publications/poll-etal-2006b.pdf
[3] http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2005Mar/0079.html
[4] http://dblab.sogang.ac.kr/icde06/workshops/data/055_SWDB02.pdf
Received on Sunday, 9 July 2006 13:12:11 GMT

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