Question: Find the public speaker who spoke on the Berlin Wall, what city was he later assasinated in?
Answer(s):
answer: Dallas

SPARQL query:
PREFIX ns: <http://rdf.freebase.com/ns/>
SELECT DISTINCT ?x
WHERE {
FILTER (?x != ?c)
FILTER (!isLiteral(?x) OR lang(?x) = '' OR langMatches(lang(?x), 'en'))
?c ns:event.public_speaker.speeches_or_presentations ?k .
?k ns:event.speech_or_presentation.speech_topic ns:m.017f5 . 
?c ns:people.deceased_person.place_of_death ?x .
}