Question: What thing was invented by both Thomas Edison and Joseph Swan?
Answer(s):
answer: Incandescent light bulb

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ns:m.07bty)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
ns:m.07bty ns:law.inventor.inventions ?x .
?x ns:law.invention.inventor ns:m.0109ts . 
}