TRS:
 {                lt(0(), s(x)) -> true(),
                     lt(x, 0()) -> false(),
                 lt(s(x), s(y)) -> lt(x, y),
                      fibo(0()) -> fib(0()),
                   fibo(s(0())) -> fib(s(0())),
                  fibo(s(s(x))) -> sum(fibo(s(x)), fibo(x)),
                       fib(0()) -> s(0()),
                    fib(s(0())) -> s(0()),
                   fib(s(s(x))) -> if(true(), 0(), s(s(x)), 0(), 0()),
   if(true(), c, s(s(x)), a, b) -> if(lt(s(c), s(s(x))), s(c), s(s(x)), b, c),
  if(false(), c, s(s(x)), a, b) -> sum(fibo(a), fibo(b)),
                    sum(x, 0()) -> x,
                   sum(x, s(y)) -> s(sum(x, y))}
 Fail