TASK DEFINITION: Given a factoid/trivia type question, generate the topic of the question. The topic is the entity the question talks about.
PROBLEM: Which horse won the 2009 Epsom Derby?

SOLUTION: 2009 epsom derby

PROBLEM: Alexander the Great died in which ancient city?

SOLUTION: alexander the great

PROBLEM: Who wrote the music for Berthold Brecht's `The Beggars Opera'?

SOLUTION:
bertolt brecht