Question: How many races have the horses bred by Jacques Van't Hart participated in?
SPARQL query:
PREFIX prop: <http://dbpedia.org/property/>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT COUNT(?uri) WHERE { ?x onto:breeder <http://dbpedia.org/resource/Jacques_Van't_Hart> . ?x prop:race ?uri  . }