States: a state consists of an ordered sequence of three numbers representing the number of missionaries, cannibals, and boats on the bank of the river from which they started. Thus, the start state is (3,3,1).
Operators: from each state the possible operators are to take either one missionary, one cannibal, two missionaries, two cannibals, or one of each across in the boat.
Thus, there ! are at most five operators, although most states have fewer because it is necessary to avoid j illegal states.
Goal test: reached state (0,0,0).
Path cost: number of crossings.