Conspiracy

Are you the man they call Grunfeld? I asked.
He said, some people call me Grunfeld.

Who calls you Grunfeld? I asked
He said, Katzenellenbogen calls me Grunfeld.

Are you in fact Grunfeld? I asked.
He said, I may be Grunfeld.

Why only may be? I asked.
He said, because I may not be Grunfeld.

Why not? I asked.
He said, because I may be Greenfield.

Are you Greenfield? I asked.
He said, I'm Greenfield if you're Appleyard.

And if I'm Apfelfeld? I asked.
He said, in that case I'm Grunfeld.