count-11.arq

jena2.5.4推理机系统的一种最基本实现 HP实验室出品

PREFIX : <http://example/>
PREFIX rdf:    <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

SELECT count(distinct ?p)
{
    # UNION is asymmetric in what it generates
    { ?x rdf:type :X . } UNION { ?x rdf:type :X . FILTER (?x != :x2 )}
    # and :x2 :p 2 with ":p 2" occuring twice.
    OPTIONAL { ?x :p ?p . }
    OPTIONAL { ?x :n ?n . }
}