TRS: { fib(0()) -> 0(), fib(s(0())) -> s(0()), fib(s(s(0()))) -> s(0()), fib(s(s(x))) -> sp(g(x)), g(0()) -> pair(s(0()), 0()), g(s(0())) -> pair(s(0()), s(0())), g(s(x)) -> np(g(x)), sp(pair(x, y)) -> +(x, y), np(pair(x, y)) -> pair(+(x, y), x), +(x, 0()) -> x, +(x, s(y)) -> s(+(x, y))} Fail