TRS:
 {                fib(N) -> sel(N, fib1(s(0()), s(0()))),
              fib1(X, Y) -> cons(X, fib1(Y, add(X, Y))),
             add(0(), X) -> X,
            add(s(X), Y) -> s(add(X, Y)),
   sel(0(), cons(X, XS)) -> X,
  sel(s(N), cons(X, XS)) -> sel(N, XS)}
 Fail