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% Here is the riddle as stated by Einstein:

% In a street there are five houses, painted five different colours.
% - In each house lives a person of different nationality
% - These five homeowners each drink a different kind of beverage, smoke different brand of cigar and keep a different pet
% - Who drinks water? Who owns the zebra?

% 1. There are five houses.
% 2. The Englishman lives in the red house.
% 3. The Spaniard owns the dog.
% 4. Coffee is drunk in the green house.
% 5. The Ukrainian drinks tea.
% 6. The green house is immediately to the right of the ivory house.
% 7. The Old Gold smoker owns snails.
% 8. Kools are smoked in the yellow house.
% 9. Milk is drunk in the middle house.
% 10. The Norwegian lives in the first house.
% 11. The man who smokes Chesterfields lives in the house next to the man with the fox.
% 12. Kools are smoked in the house next to the house where the horse is kept.
% 13. The Lucky Strike smoker drinks orange juice.
% 14. The Japanese smokes Parliaments.
% 15. The Norwegian lives next to the blue house.

% 1. There are five houses. They maintain a list.
houses(0, []) :- !.
houses(N, [(_Person,_Color,_Drink,_Smoke,_Animal)|T]) :- N1 is N-1, houses(N1,T).

% 2. The Englishman lives in the red house.
rule2([(brit,red,_,_,_)|_]).
rule2([_|T]) :- rule2(T).

% 3. The Spaniard owns the dog.
rule3([(spaniard,_,_,_,dog)|_]).
rule3([_|T]) :- rule3(T).

% 4. Coffee is drunk in the green house.
rule4([(_,green,coffee,_,_)|_]).
rule4([_|T]) :- rule4(T).

% 5. The Ukrainian drinks tea.
rule5([(ukranian,_,tea,_,_)|_]).
rule5([_|T]) :- rule5(T).

% 6. The green house is immediately to the right of the ivory house.
rule6([(_,ivory,_,_,_),(_,green,_,_,_)|_]).
rule6([_|T]) :- rule6(T).

% 7. The Old Gold smoker owns snails.
rule7([(_,_,_,old_gold,snake)|_]).
rule7([_|T]) :- rule7(T).

% 8. Kools are smoked in the yellow house.
rule8([(_,yellow,_,kool,_)|_]).
rule8([_|T]) :- rule8(T).

% 9. Milk is drunk in the middle house.
rule9([_,_,(_,_,milk,_,_),_,_]).
rule9([_|T]) :- rule9(T).

% 10. The Norwegian lives in the first house.
rule10([(norwegian,_,_,_,_)|_]).

% 11. The man who smokes Chesterfields lives in the house next to the man with the fox.
rule11([(_,_,_,chesterfield,_),(_,_,_,_,fox)|_]).
rule11([(_,_,_,_,fox),(_,_,_,chesterfield,_)|_]).
rule11([_|T]) :- rule11(T).

% 12. Kools are smoked in the house next to the house where the horse is kept.
rule12([(_,_,_,kool,_),(_,_,_,_,horse)|_]).
rule12([(_,_,_,_,horse),(_,_,_,kool,_)|_]).
rule12([_|T]) :- rule12(T).

% 13. The Lucky Strike smoker drinks orange juice.
rule13([(_,_,orange,lucky_strike,_)|_]).
rule13([_|T]) :- rule13(T).

% 14. The Japanese smokes Parliaments.
rule14([(japaneze,_,_,parliament,_)|_]).
rule14([_|T]) :- rule14(T).

% 15. The Norwegian lives next to the blue house.
rule15([(norwegian,_,_,_,_),(_,blue,_,_,_)|_]).
rule15([(_,blue,_,_,_),(norwegian,_,_,_,_)|_]).
rule15([_|T]) :- rule15(T).

% After that, we are to specify the questions:
quest1(WaterDrinker,[(WaterDrinker,_,water,_,_)|_]).
quest1(WaterDrinker,[_|T]) :- quest1(WaterDrinker,T).

quest2(ZebraOwner,[(ZebraOwner,_,_,_,zebra)|_]).
quest2(ZebraOwner,[_|T]) :- quest2(ZebraOwner,T).

% Solutiontime!
solution(Persons,WaterDrinker,ZebraOwner) :-
  houses(5,Persons),

  rule2(Persons),
  rule3(Persons),
  rule4(Persons),
  rule5(Persons),
  rule6(Persons),
  rule7(Persons),
  rule8(Persons),
  rule9(Persons),
  rule10(Persons),
  rule11(Persons),
  rule12(Persons),
  rule13(Persons),
  rule14(Persons),
  rule15(Persons),
  
  quest1(WaterDrinker,Persons),
  quest2(ZebraOwner,Persons).

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