Title: Frederic Chopin.
Question: Who was the director of the Academy of Art that Frederic met while in Dusseldorf?

Title: Data compression.
Question: What are often called psychoacoustic models?

Title: Heresy.
Question: After what two events did various Christian churches also begin using the first seven Ecumenical Councils to identify heresy?

Title: John von Neumann.
Question:
What type of "off color" humor did Von Neumann especially enjoy?