**And-Or-Graph-Search**algorithm in Figure and-or-graph-search-algorithm checks for repeated states only on the path from the root to the current state. Suppose that, in addition, the algorithm were to store

*every*visited state and check against that list. (See in Figure breadth-first-search-algorithm for an example.) Determine the information that should be stored and how the algorithm should use that information when a repeated state is found. (*Hint*: You will need to distinguish at least between states for which a successful subplan was constructed previously and states for which no subplan could be found.) Explain how to use labels, as defined in Section cyclic-plan-section, to avoid having multiple copies of subplans.

The **And-Or-Graph-Search** algorithm in
Figure and-or-graph-search-algorithm checks for
repeated states only on the path from the root to the current state.
Suppose that, in addition, the algorithm were to store
*every* visited state and check against that list. (See in
Figure breadth-first-search-algorithm for an example.)
Determine the information that should be stored and how the algorithm
should use that information when a repeated state is found.
(*Hint*: You will need to distinguish at least between
states for which a successful subplan was constructed previously and
states for which no subplan could be found.) Explain how to use labels,
as defined in Section cyclic-plan-section, to avoid
having multiple copies of subplans.