EXPORT     WolfGoatCabbage.

% The wolf-goat-cabbage problem, as described in Sterling and Shapiro,
% The Art of Prolog, pages 285-287.

IMPORT     Lists, Sets.

BASE       Object, State, Move.

CONSTANT   Farmer, Wolf, Goat, Cabbage : Object.

FUNCTION   St : Set(Object) * Set(Object) -> State;
           LeftToRight : Set(Object) -> Move;
           RightToLeft : Set(Object) -> Move.

PREDICATE  Initial, Final : State;
           Applicable : Move * State;
           ApplyMove : Move * State * State;
           Legal : State.