MAYBE

'Pop* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  a__f(a(), X, X) -> a__f(X, a__b(), b())
     , a__b() -> a()
     , mark(f(X1, X2, X3)) -> a__f(X1, mark(X2), X3)
     , mark(b()) -> a__b()
     , mark(a()) -> a()
     , a__f(X1, X2, X3) -> f(X1, X2, X3)
     , a__b() -> b()}

Proof Output:    
  The input cannot be shown compatible