  We have revisited the electronic structure of infinite-layer RNiO$_2$ (R= La,
Nd) in light of the recent discovery of superconductivity in Sr-doped
NdNiO$_2$. From a comparison to their cuprate counterpart CaCuO$_2$, we derive
essential facts related to their electronic structures, in particular the
values for various hopping parameters and energy splittings, and the influence
of the spacer cation. From this detailed comparison, we comment on expectations
in regards to superconductivity. In particular, both materials exhibit a large
ratio of longer-range hopping to near-neighbor hopping which should be
conducive for superconductivity.
