MAYBE

'epo* (timeout of 60.0 seconds)'
--------------------------------
Answer:           MAYBE
Input Problem:    innermost runtime-complexity with respect to
  Rules:
    {  plus(0(), y) -> y
     , plus(s(x), y) -> s(plus(x, y))
     , lt(0(), s(y)) -> true()
     , lt(x, 0()) -> false()
     , lt(s(x), s(y)) -> lt(x, y)
     , fib(x) -> fibiter(x, 0(), 0(), s(0()))
     , fibiter(b, c, x, y) -> if(lt(c, b), b, c, x, y)
     , if(false(), b, c, x, y) -> x
     , if(true(), b, c, x, y) -> fibiter(b, s(c), y, plus(x, y))}

Proof Output:    
  The input cannot be shown compatible