SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/property/author> <http://dbpedia.org/resource/Terry_Pratchett> . ?x <http://dbpedia.org/ontology/nonFictionSubject> ?uri . }
Terry Pratchett has written about how many topics?
SELECT DISTINCT COUNT ( ?m ) WHERE { ?x property:author resource:Terry_Pratchett . ?x property:non_fiction_subject ?m . }
291
There are [291] subjects of the books authored by Terry Pratchett.
There are [291] themes in Terry Pratchett's books.
[291] subject are there, of the books whose author is him .
There are [291] topics of which he is the author.
There are [291] subjects of the books whose author is the person .
There are [291] topics that are authored by the person.