Because the agent does not directly

Because the agent does not directly observe the environment's state, the agent must make decisions under uncertainty of the true environment state.
However, by interacting with the environment and receiving observations, the agent may update its belief in the true state by updating the probability distribution of the current state.
A consequence of this property is that the optimal behavior may often include information gathering actions that are taken purely because they improve the agent's estimate of the current state, thereby allowing it to make better decisions in the future.

It is instructive to compare the above definition with the definition of a Markov decision process. An MDP does not include the observation set, because the agent always knows with certainty the environment's current state. Alternatively, an MDP can be reformulated as a POMDP by setting the observation set to be equal to the set of states and defining the observation conditional probabilities to deterministically select the observation that corresponds to the true state.

結果 (繁體中文) 2:

由於代理不直接觀測環境的狀態下，代理人必須在真實的環境狀態的不確定性做出的決定。
但是，通過與環境的交互和接收的觀測，代理可以通過更新概率分佈更新它的真實狀態的信仰目前的狀態。
這個屬性的一個後果是，最優行為往往包括信息收集是採取純粹是因為它們提高的當前狀態的代理的估計，從而使其能夠在未來做出更好的決策行動。這是有益的上面的定義與一個Markov決策過程的定義進行比較。MDP中不包括觀測集，因為代理總是肯定的環境的當前狀態知道。可選地，MDP可以通過設置觀察設定為等於該組狀態和限定所述觀測條件概率確定性地選擇對應於所述真實狀態的觀察來重新作為POMDP。

結果 (繁體中文) 3:

因為代理不直接觀察環境的狀態，代理必須在不確定的環境狀態下做出决定。然而，通過與環境和接受觀察，代理可以更新其信仰的真實狀態，通過更新的概率分佈的當前狀態。
此内容的結果是，最佳的行為可能會經常包括資訊收集行動，採取純粹是因為他們提高了代理的估計，現時的狀態，從而使其作出更好的决定，在未來。MDP不包括觀測集，因為代理總是知道環境的當前狀態。另外，MDP可以重新設定設定為等於狀態的設定和定義的觀察條件概率來確定選擇對應於真實狀態的觀察觀察POMDP。