Question: Who was the president during the time the opponent of John Hospers was in the office?
SPARQL query: SELECT DISTINCT ?uri WHERE { ?x <http://dbpedia.org/ontology/opponent> <http://dbpedia.org/resource/John_Hospers> . ?x <http://dbpedia.org/ontology/incumbent> ?uri  . }
Answer: The incumbent of the politician whose opponent is John Hospers is [Richard Nixon].