Question: Which  person has opponent Ike Clanton?
SPARQL:
SELECT DISTINCT ?uri WHERE {?uri <http://dbpedia.org/ontology/opponent> <http://dbpedia.org/resource/Ike_Clanton> . ?uri <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <http://dbpedia.org/ontology/Person>}