machine_question: what were adolf hitler 's parents names and the person's date of death is earliest
question: Of both of Adolf Hitler's parents names, the name of the parent with the earliest date of death?
sparql: PREFIX ns: <http://rdf.freebase.com/ns/>
  SELECT DISTINCT ?x
  WHERE {
  FILTER (?x != ns:m.07_m9_)
  FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
  ns:m.07_m9_ ns:people.person.parents ?x .
  ?x ns:people.deceased_person.date_of_death ?num .
  }
  ORDER BY ?num LIMIT 1
webqsp_question: what were adolf hitler 's parents names