MAYBE

'Pop* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  rev(ls) -> r1(ls, empty())
     , r1(empty(), a) -> a
     , r1(cons(x, k), a) -> r1(k, cons(x, a))}

Proof Output:    
  The input cannot be shown compatible