Exercise 8.8 In a forward planner, you can represent a state in terms of the sequence of actions that lead to that state.

(a) Explain how to check if the precondition of an action is satisfied, given such a representation.

(b) Explain how to do cycle detection in such a representation. You can assume that all of the states are legal. (Some other program has ensured that the preconditions hold.)

[Hint: Consider the composite action (Exercise 8.7) consisting of the first k or the last k actions at any stage.]