Abstract Given any compact Hausdorff space X, we present a simple proof that a continuous function g C (X) g ∈ C (X) can be uniformly approximated on X by elements of some linear subspace L C (X) L ⊂ C (X), if and only if g can be pointwise approximated on X by some equibounded sequence in L L. Moreover, given any compactum K C K ⊂ C, we also show that every f C (K) f ∈ C (K) can be uniformly approximated by rational functions (without poles on K), if and only if the complex conjugate w w w ↦ w ¯ can be pointwise approximated by functions holomorphic on K (no equibounded hypothesis required).
Zeron et al. (Mon,) studied this question.