Question: How many books are there whose author's tomb is in Madrid?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT COUNT(?uri) WHERE { ?x onto:restingPlace <http://dbpedia.org/resource/Madrid> . ?uri onto:author ?x  . ?uri rdf:type onto:Book}