# Based on
# http://lists.w3.org/Archives/Public/public-rdf-dawg/2004OctDec/0554.html
PREFIX : <http://example.org/ns#>
SELECT $a $c
WHERE { $a :b $c .
OPTIONAL { $c :d $e } .
FILTER ( !BOUND($e) )
}
# Based on
# http://lists.w3.org/Archives/Public/public-rdf-dawg/2004OctDec/0554.html
PREFIX : <http://example.org/ns#>
SELECT $a $c
WHERE { $a :b $c .
OPTIONAL { $c :d $e } .
FILTER ( !BOUND($e) )
}