Question: Name the airlines which have a hub in airport in SF?
SPARQL query:
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX prop: <http://dbpedia.org/property/>
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?uri WHERE { ?x prop:cityServed <http://dbpedia.org/resource/San_Francisco> . ?uri prop:hubs ?x  . ?uri rdf:type onto:Airline}