MAYBE

'Pop* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  null(nil()) -> true()
     , null(add(n, x)) -> false()
     , tail(add(n, x)) -> x
     , tail(nil()) -> nil()
     , head(add(n, x)) -> n
     , app(nil(), y) -> y
     , app(add(n, x), y) -> add(n, app(x, y))
     , reverse(nil()) -> nil()
     , reverse(add(n, x)) -> app(reverse(x), add(n, nil()))
     , shuffle(x) -> shuff(x, nil())
     , shuff(x, y) -> if(null(x), x, y, app(y, add(head(x), nil())))
     , if(true(), x, y, z) -> y
     , if(false(), x, y, z) -> shuff(reverse(tail(x)), z)}

Proof Output:    
  The input cannot be shown compatible