original_query: Who is Isaac Ackerman and what is his connection to Chaliapin?
query: Who is Isaac Ackerman and what is his connection to Feodor Chaliapin?
answer: Isaac Ackerman is a pseudonym used by Nelson Eddy. Under this name, he wrote a biopic screenplay about Feodor Chaliapin, in which he planned to play the lead role and also a younger version of himself.