database
    entry(symbol,integer,integer,integer,integer)
    
domains
    Left_miss,Left_cann,Right_miss,Right_cann=integer
    Total_miss,Total_cann=integer
    New_left_miss,New_left_cann,New_right_miss,New_right_cann=integer
    person1,person2=integer
    
predicates
    boat_state(integer,integer)
    zero(integer,integer)
    go(symbol,integer,integer,integer,integer)
    validate(integer,integer,integer,integer)
    
clauses
    boat_state(1,1).
    boat_state(1,0).
    boat_state(0,2).
    boat_state(0,1).
    boat_state(2,0).

    zero(X,Y):-
        X=0,Y<>0.

    validate(Left_miss,Left_cann,Right_miss,Right_cann):-
        Total_miss=Left_miss+Right_miss,
        Total_cann=Left_cann+Right_cann,
        Total_miss=3,Total_cann=3,
        Left_miss>=0,Left_cann>=0,
        Right_miss>=0,Right_cann>=0,
        Left_miss>=Left_cann,Right_miss>=Right_cann.

    validate(Left_miss,Left_cann,Right_miss,Right_cann):-
        Total_miss=Left_miss+Right_miss,
        Total_cann=Left_cann+Right_cann,
        Total_miss=3,Total_cann=3,
        Left_miss>=0,Left_cann>=0,
        Right_miss>=0,Right_cann>=0,
        zero(Left_miss,Left_cann);

        Total_miss=Left_miss+Right_miss,
        Total_cann=Left_cann+Right_cann,
        Total_miss=3,Total_cann=3,
        Left_miss>=0,Left_cann>=0,
        Right_miss>=0,Right_cann>=0,
        zero(Right_miss,Right_cann).

    go(_,0,0,3,3):-
        write("\nProblem Solved").

    go(left_to_right,Left_miss,Left_cann,Right_miss,Right_cann):-
        boat_state(Person1,Person2),
        New_left_miss=Left_miss-Person1,
        New_left_cann=Left_cann-Person2,
        New_right_miss=Right_miss+Person1,
        New_right_cann=Right_cann+Person2,
        not(entry(right_to_left,New_left_miss,New_left_cann,New_right_miss,New_right_cann)),
        validate(New_left_miss,New_left_cann,New_right_miss,New_right_cann),
        assert(entry(right_to_left,New_left_miss,New_left_cann,New_right_miss,New_right_cann)),
        write("Left to right \t",New_left_miss," ",New_left_cann," \t",Person1," ",Person2," \t",New_right_miss," ",New_right_cann),nl,
        go(right_to_left,New_left_miss,New_left_cann,New_right_miss,New_right_cann).
        
    go(right_to_left,Left_miss,Left_cann,Right_miss,Right_cann):-
        boat_state(Person1,Person2),
        New_left_miss=Left_miss+Person1,
        New_left_cann=Left_cann+Person2,
        New_right_miss=Right_miss-Person1,
        New_right_cann=Right_cann-Person2,
        not(entry(left_to_right,New_left_miss,New_left_cann,New_right_miss,New_right_cann)),
        validate(New_left_miss,New_left_cann,New_right_miss,New_right_cann),
        assert(entry(left_to_right,New_left_miss,New_left_cann,New_right_miss,New_right_cann)),
        write("Right to left \t",New_left_miss," ",New_left_cann," \t",Person1," ",Person2," \t",New_right_miss," ",New_right_cann),nl,nl,
        go(left_to_right,New_left_miss,New_left_cann,New_right_miss,New_right_cann).
goal
    clearwindow(),
    write("Intial State  \t",3," ",3," \t",0," ",0," \t",0," ",0," "),nl,nl,
    assert(entry(left_to_right,3,3,0,0)),
    go(left_to_right,3,3,0,0).


Output

Intial State    3 3     0 0     0 0

Left to right   2 2     1 1     1 1
Right to left   3 2     1 0     0 1

Left to right   3 0     0 2     0 3
Right to left   3 1     0 1     0 2

Left to right   1 1     2 0     2 2
Right to left   2 2     1 1     1 1

Left to right   0 2     2 0     3 1
Right to left   0 3     0 1     3 0

Left to right   0 1     0 2     3 2
Right to left   1 1     1 0     2 2

Left to right   0 0     1 1     3 3

Problem Solved