Question: Who was Lincoln's Vice president and the 15th U.S. Vice President?
Answer(s):
answer: Hannibal Hamlin

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.0gzh)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.0gzh ns:government.us_president.vice_president ?x .
?x ns:government.us_vice_president.vice_president_number "15" . 
}