Is there a problem that has only a recursive solution?
algorithm, recursion
Solution
The Ackermann function cannot be expressed without recursion
edit: As noted in another answer, this is incorrect.
Problem
Possible Duplicates: Is there a problem that has only a recursive solution? Can every recursion be converted into iteration? “Necessary” Uses of Recursion in Imperative Languages Is there a problem that has only a recursive solution, that is, a problem that has a recursive solution, but an iterative solution has yet to be found, or better yet, has proven to be non-existing (obviously, this is not a tail-recursion)?