MAYBE

'Pop* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  rev(a()) -> a()
     , rev(b()) -> b()
     , rev(++(x, y)) -> ++(rev(y), rev(x))
     , rev(++(x, x)) -> rev(x)}

Proof Output:    
  The input cannot be shown compatible