> Here's my attempt. I think we can get the simplification rule machinery
> to do some of the work for us. Here cc matches an expression which is
Thank you. It seems your solution does not treat functions of E(x) as
constants (although I think it was ambiguous in my message). How extend
it to deal with the following?
(%i8) E(f(E(x)));
(%o8) E(f(E(x)))
(%i9) ''%;
(%o9) E(f(E(x))) <---- should be f(E(x))