4.monkey_banana.prolog

in_room(monkey).
in_room(banana).
in_room(chair).

clever(monkey).
can_climb(monkey, chair).
tall(chair).
can_move(monkey, chair, banana).

can_reach(X, Y):-
  under(Z, Y),
  tall(Z),
  can_climb(X, Z),
  clever(X).

under(X, Y):-
  can_move(Z, X, Y),
  in_room(X), 
  in_room(Y), 
  in_room(Z),
  clever(Z).

5.medical_diagnosis.prolog

symptom(charlie,fever).
symptom(charlie,headache).
symptom(charlie,runnynose).
symptom(charlie,rash).
hypothesis(Patient,measles) :- 
    symptom(Patient,fever),
    symptom(Patient,cough), 
    symptom(Patient,conjunctive), 
    symptom(Patient,runnynose), 
    symptom(Patient,rash).
hypothesis(Patient,germanmeasles):- 
    symptom(Patient,fever),
    symptom(Patient,headache),
    symptom(Patient,runnynose),
    symptom(Patient,rash).
hypothesis(Patient,flu):- 
    symptom(Patient,fever),
    symptom(Patient,headache),
    symptom(Patient,bodyache), 
    symptom(Patient,chills), 
    symptom(Patient,sorethrought),
    symptom(Patient,cough), 
    symptom(Patient,conjunctive), 
    symptom(Patient,conjunctive),
    symptom(Patient,runnynose).
hypothesis(Patient,commoncold):-
    symptom(Patient,headache),
    symptom(Patient,runnynose), 
    symptom(Patient,snuzing),
    symptom(Patient,chills),
    symptom(Patient,sorethrought).
hypothesis(Patient,mumps):-
    symptom(Patient,fever),
    symptom(Patient,swallenglands).
hypothesis(Patient,chikenpox):-
    symptom(Patient,fever),
    symptom(Patient,rash),
    symptom(Patient,bodyache).
hypothesis(Patient,whooping-cough):-
    symptom(Patient,runnynose),
    symptom(Patient,snuzing),
    symptom(Patient,cough).

6.factorial.prolog

factorial(0, 1).
factorial(X, Result):-
  X > 0,
  X1 is X - 1,
  factorial(X1, R1),
  Result is X * R1.

fibonacci(N, Y):-
  N > 0,
  fibo_series(N, Y, _).

fibo_series(1, 1, 0).
fibo_series(N, Y, Y1):-
  N1 is N - 1,
  fibo_series(N1, Y1, Y2),
  Y is Y1 + Y2.

7.n_queens.prolog

use_module(library(clpfd)).

n_queens(N, Qs) :-
    length(Qs, N),
    Qs ins 1..N,
    safe_queens(Qs).

safe_queens([]).
safe_queens([Q|Qs]) :- safe_queens(Qs, Q, 1), safe_queens(Qs).

safe_queens([], _, _).
safe_queens([Q|Qs], Q0, D0) :-
    Q0 #\= Q,
    abs(Q0 - Q) #\= D0,
    D1 #= D0 + 1,
    safe_queens(Qs, Q0, D1).
    
% n_queens(8, Qs), label(Qs).

8.traveling_salesman.prolog

road(1,2,50).
road(1,3,100).
road(1,4,75).
road(1,5,65).
road(2,5,30).
road(3,4,40).
road(3,7,50).
road(4,5,25).
road(4,6,30).
road(4,9,65).
road(4,7,70).
road(5,6,30).
road(6,9,35).

route(Town1, Town2, Distance):-
    road(Town1, Town2, Distance).
route(Town1, Town2, Distance):-
    road(Town1, X, Dist1),
    route(X, Town2, Dist2),
    Distance is Dist1 + Dist2.

9.water_jug.prolog

solve(A,B):-                                      %Input packaging
moves([s(A,B)],RevStates),                        %add list
reverse(RevStates,States),                        %reverse answers
write(States),nl,fail.                            %write and find all answer.                     

moves([s(X0,Y0)|T], [s(2,Y1),s(X0,Y0)|T])         %set goal
   :- action(s(X0,Y0),s(2,Y1)), !.                %cut off when find answer

moves([s(X0,Y0)|T],States) :-                
   action(s(X0,Y0),s(X1,Y1)),                     %find next node
    not(member(s(X1,Y1),[s(X0,Y0)|T])),           %not look for past nodes
    moves([s(X1,Y1),s(X0,Y0)|T],States).          %repeat moves
	

action(s(X,Y),s(Z,3)) :-    %from left jug to right jug until right full
X=<4,X>0,Y>=0,Y<3,Z is X - (3 - Y), Z >= 0.
action(s(X,Y),s(Z,0)) :-    %from right jug to left jug until right empty
X<4,X>=0,Y>0,Y=<3,Z is X + Y, Z =< 4.
action(s(X,Y),s(4,Z)) :-    %from right jug to left jug until left full 
X<4,X>=0,Y>0,Y=<3,Z is Y - (4 - X), Z >=0.
action(s(X,Y),s(0,Z)) :-    %from left jug to right jug until left empty
X=<4,X>0,Y>=0,Y<3,Z is X + Y, Z =< 3.

action(s(X,Y),s(4,Y)):-     %fill left jug (4) 
X<4,X>=0,Y>=0,Y=<3.
action(s(X,Y),s(X,3)):-     %fill right jug (3)
X=<4,X>=0,Y>=0,Y<3.
action(s(X,Y),s(X,0)) :-    %empty right jug 
X=<4,X>=0,Y>0,Y=<3.
action(s(X,Y),s(0,Y)) :-    %empty left jug 
X=<4,X>0,Y>=0,Y=<3.