 Solution

ID: past-exam-of-the-computer-science-course-of-the-university-of-oxford/2023/artificial-intelligence/2/h/solution

Write

F, R, C

for the three item constants,

E, W

for the banks,

L, U, M

for the corrected load, unload and move actions, and

K_{s}

for

Check (s, p_{F}, p_{R}, p_{C})

instantiated with the items' actual current locations. A fully executable plan in the STRIPS model of part (g) is

L (R, E), K_{E}, M (E, W), U (R, W), K_{W}, M (W, E), L (F, E), K_{E}, M (E, W), U (F, W), L (R, W), K_{W}, M (W, E), U (R, E), L (C, E), K_{E}, M (E, W), U (C, W), K_{W}, M (W, E), L (R, E), K_{E}, M (E, W), U (R, W) .

Thus the seven crossings carry rabbit west, nothing east, fox west, rabbit east, carrot west, nothing east, rabbit west.

Immediately before those crossings, the items left on the departure bank are respectively

{F, C}, {R}, {C}, {F}, {R}, {F, C}, \emptyset

. None contains an incompatible pair, so each displayed

K_{s}

has its safety preconditions. Each loaded crossing carries exactly one item, and all three finish west.

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