Update officer_problem.pl

officer_problem.pl

@@ -7,15 +7,15 @@ officer_problem(N, Square) :-
         maplist(set_inner_length(2), Square),
         append(Square, Vs),
         maplist(set_domain(N), Vs),
-        square2lists(Square, L1, L2),
-        maplist(all_different,L1),
-        maplist(all_different,L2),
+        square2lists(Square, Xs, Ys),
+        maplist(all_different,Xs),
+        maplist(all_different,Ys),
         transpose(Square, TransposedSquare),
-        square2lists(TransposedSquare, L3, L4),
-        maplist(all_different,L3),
-        maplist(all_different,L4),
+        square2lists(TransposedSquare, TXs, TYs),
+        maplist(all_different, TXs),
+        maplist(all_different, TYs),
         maplist(labeling([]), Vs),
-        unique_combination(Square),
+        unique_combination_xy(Square),
         maplist(portray_clause, Square).       
 
 set_inner_length(_,[]) :- !.
@@ -34,21 +34,21 @@ square2lists([[H|TH]|TR], [[H1|T1]|TR1], [[H2|T2]|TR2]) :-
         H = [H1,H2],
         square2lists([TH|TR], [T1|TR1], [T2|TR2]).
         
-unique_combination([_]) :- !.
-unique_combination([H|T]) :-
-        unique_combination(H,T),
-        unique_combination(T).
+unique_combination_xy([_]) :- !.
+unique_combination_xy([H|T]) :-
+        unique_combination_xy(H,T),
+        unique_combination_xy(T).
 
-unique_combination([],_) :- !.
-unique_combination([H|T],Lists) :-
+unique_combination_xy([],_) :- !.
+unique_combination_xy([H|T],Lists) :-
         H = [H1,H2],
-        unique_combination(H1, H2, Lists),
-        unique_combination(T, Lists).
+        unique_combination_xy(H1, H2, Lists),
+        unique_combination_xy(T, Lists).
                   
-unique_combination(_,_,[]) :- !.
-unique_combination(E1, E2, [[H|TH]|TR]) :-
+unique_combination_xy(_,_,[]) :- !.
+unique_combination_xy(E1, E2, [[H|TH]|TR]) :-
         H = [H1,H2],
-        (H1 == E1 -> (H2 #\= E2, unique_combination(E1, E2, TR));
-        unique_combination(E1, E2, [TH|TR])).
+        (H1 == E1 -> (H2 #\= E2, unique_combination_xy(E1, E2, TR));
+        unique_combination_xy(E1, E2, [TH|TR])).