Note that $\max+{i \in R} \left( h_{iB} \right)$ does not actually take a max, as the states are ordered, it's the hitting probability from the 'highest' state in the reasonable region.
What about in more than one dimension? Then there is more than one boundary state (e.g. (1, B), (2, B), ... (B-1, B), (B, B)). Let $\tilde{B}$ denote the set of boundary states.
Do we:
Take $H{R\tilde{B}} = \max{i \in R, b \in \tilde{B}} \left( h{ib} \right)$ ? That is $H{RB}$ is the highest probability of hitting a boundary state from the reasonable region.
Or Take $H{R\tilde{B}} = \max{i \in R} \left( \cup{b \in \tilde{B}} h{i b} \right)$ ? That is $H_{RB}$ is the probability of hitting any of the boundary states from the reasonable region.
Note that $\max+{i \in R} \left( h_{iB} \right)$ does not actually take a
max
, as the states are ordered, it's the hitting probability from the 'highest' state in the reasonable region.