Planning Under Uncertainty

As in Part II, it also seems appropriate to give two names to Part III. It is officially called decision-theoretic planning, but it can also be considered as planning under uncertainty. All of the concepts in Parts I and II avoided models of uncertainties. Chapter 8 considered plans that can overcome some uncertainties, but there was no explicit modeling of uncertainty.

In this part, uncertainties generally interfere with two aspects of planning:

1. Predictability: Due to uncertainties, it is not known what will happen in the future when certain actions are applied. This means that future states are not necessarily predictable.
2. Sensing: Due to uncertainties, the current state is not necessarily known. Information regarding the state is obtained from initial conditions, sensors, and the memory of previously applied actions.

These two kinds of uncertainty are independent in many ways. Each has a different effect on the planning problem.