The exact representation of symmetric polynomials on Banach spaces with
symmetric basis and also on
separable rearrangement-invariant function spaces over [0, 1] and
[0, ∞) is given. As a consequence of this
representation it is obtained that, among these spaces,
[lscr ]2n, L2n[0, 1],
L2n[0, ∞) and
L2n[0, ∞)∩L2m[0, ∞)
where n, m are both integers are the only spaces that
admit separating polynomials.