What is the {human} for {doctoral student} of {Carl Sagan}
Who is Carl Sagan's doctoral student?
Who is Carl Sagan's doctoral student?
SELECT DISTINCT ?p WHERE { ?p rdf:type ontology:human . resource:Carl_Sagan property:doctoral_student ?p }
select distinct ?obj where { ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q410> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P185> . ?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj . ?obj <http://www.wikidata.org/entity/P31> <http://wikidata.dbpedia.org/resource/Q5> } 
 select distinct ?obj where { wd:Q410 wdt:P185 ?obj . ?obj wdt:P31 wd:Q5 } 
James B. Pollack Steven W. Squyres Steven Soter Owen Toon