Conversation so far:
Who is Frank Rich in relation to Stephen Sondheim?
On April 28, 2002, Stephen Sondheim and Frank Rich of the New York Times had a conversation.
What were the conversations between Stephen Sondheim and Frank Rich about?
In connection with the Sondheim Celebration, Stephen Sondheim and Frank Rich of the New York Times had a conversation.

Question: What was the celebration for?
Self-contained rewrite: What was the Sondheim Celebration in 2002 for?