PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> 
PREFIX rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX owl:  <http://www.w3.org/2002/07/owl#> 

SELECT distinct ?p ?a1 ?a2
WHERE {
?a1 rdf:type ?p.
?a2 rdf:type ?p.
?a1 owl:differentFrom ?a2.
?p owl:oneOf _:b.
}