The plan in Figure 8, discussed in Section 4.1.3, involves just one source of uncertainty and hence contains just one decision-step. There are two possible ways of achieving the goal, one for each outcome of the uncertainty.
Initial: (AVAILABLE CAR-1) When [LOC0S: B] (PACKAGE-AT LOCATION-2) When [LOC0S: A] (PACKAGE-AT LOCATION-1) (AND (IS-CAR CAR-1) (IS-CAR CAR-2) (LOCATION LOCATION-1) (LOCATION LOCATION-2)) Step 1 (2): (ASK-ABOUT-PACKAGE) (KNOW-IF (PACKAGE-AT LOCATION-2)) 0 -> (LOCATION LOCATION-2) (KNOW-IF (PACKAGE-AT LOCATION-1)) 0 -> (LOCATION LOCATION-1) Step 2 (1): (DECIDE LOC0S) (and (PACKAGE-AT LOCATION-2) T ) => [LOC0S: B] (and (PACKAGE-AT LOCATION-1) T ) => [LOC0S: A] 1 -> (KNOW-IF (PACKAGE-AT LOCATION-2)) 1 -> (KNOW-IF (PACKAGE-AT LOCATION-1)) Step 3 (4): (DRIVE CAR-1 LOCATION-1) YES: [LOC0S: A] (AT LOCATION-1) 0 -> (AVAILABLE CAR-1) Step 4 (3): (DRIVE CAR-1 LOCATION-2) YES: [LOC0S: B] (AT LOCATION-2) 0 -> (AVAILABLE CAR-1) Goal: (AND (AT ?LOC) (PACKAGE-AT ?LOC)) GOAL YES: [LOC0S: B] 4 -> (AT LOCATION-2) 0 -> (PACKAGE-AT LOCATION-2) NO : [LOC0S: A] GOAL YES: [LOC0S: A] 3 -> (AT LOCATION-1) 0 -> (PACKAGE-AT LOCATION-1) NO : [LOC0S: B] Complete!