| 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 . } | |
| } |