Question: How many people were opponents of the ones buried in the tower of London?
SPARQL:
SELECT DISTINCT COUNT(?uri) WHERE { ?x <http://dbpedia.org/property/restingPlace> <http://dbpedia.org/resource/Tower_of_London> . ?x <http://dbpedia.org/ontology/opponent> ?uri  . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Person>}