0
$\begingroup$

Consider a Markov Decision Process where the state space $S$ and the action space $A$ are continuous and compact.

In state $s$, if action $a$ is chosen and the next state becomes $s'$, the corresponding reward is denoted by $R_a(s,s')$.

Assume that when in state $s \in S$ if action $a \in A$ is played, then the next state $s' \in S$ is a deterministic function of $s$ and $a$, i.e., $s' = f(s,a) \ \forall s\in S, a\in A$. Notice that this implies that the reward too is a function of $a$ and $s$ only, i.e., we can write $R_a(s,s') = R_a(s)$.

Fix an initial state $s_0 \in S$. For a given time-horizon $N \in \mathbb N$, the $N$-step average reward obtained from actions $\mathbf a = (a_1, a_2, \ldots, a_N)$ and the corresponding evolution of states $\mathbf s(\mathbf a) = (s_1,s_2,\ldots,s_N)$ is \begin{align} R_N(\mathbf a) &:= \frac 1 N \sum_{t=1}^N R_{a_t}(s_{t-1},s_t)\\ &\ = \frac 1 N \sum_{t=1}^N R_{a_t}(s_{t-1}). \end{align}

For each $N$, there is an optimal average-reward $\hat R_N := \max\limits_{\mathbf a} R_N(\mathbf a)$. We are interested in the limiting quantity $\hat R_\infty := \lim_{N\to\infty} \hat R_N$ (provided that it exists).

Question: When is $\hat R_\infty$ independent of the initial state $s_0$? What are some conditions that are sufficient for this?

It is clear that if the states are connected, i.e., if any state can be reached by any other state by finitely many actions, then the initial state does not affect $\hat R_\infty$. I am looking for answers assuming that connectivity in this sense does not hold. It is quite intuitive that even if connectivity does not hold, under some mild conditions, in the infinite-horizon the initial state $s_0$ should not matter.

Any answer/reference would be highly appreciated. Thanks in advance!

$\endgroup$
1

0

You must log in to answer this question.