Einstein Riddle with List of terms

Question

I implemented Einstein Riddle in Prolog and I\'m trying to find out who had a fish at home.
I can\'t find fault in this code and trace option is not helping with this pr

Answer 1

just to show an alternative encoding scheme:

solve :- solve(Sol, From), writeln(From), maplist(writeln, Sol).

solve(Sol, From) :-
    phrase( (from(1, norway)
        ,color(red) = from(england)
        ,color(GREEN, green), color(WHITE, white), {GREEN is WHITE-1}
        ,from(denmark) = drink(tea)
        ,smoke(Light, light), animal(Cat, cat), next_to(Light, Cat)
        ,color(Yellow, yellow), smoke(Yellow, cigar)
        ,from(germany) = smoke(waterpipe)
        ,drink(3, milk)
        ,drink(Water, water), next_to(Light, Water)
        ,animal(bird) = smoke(nofilter)
        ,from(sweden) = animal(dog)
        ,from(NORWAY, norway), color(BLUE, blue), next_to(NORWAY, BLUE)
        ,animal(HORSE, horse), next_to(HORSE, GREEN) % next_to(HORSE, Yellow)
        ,drink(beer) = smoke(menthol)
        ,color(green) = drink(coffee)
        ,animal(Fish, fish), from(Fish, From)
    ), [[1,_,_,_,_,_],
        [2,_,_,_,_,_],
        [3,_,_,_,_,_],
        [4,_,_,_,_,_],
        [5,_,_,_,_,_]
    ], Sol).

state(S), [A,B,C,D,E] --> [A,B,C,D,E], {member(S, [A,B,C,D,E])}.

color(A, B)  --> state([A,B,_,_,_,_]).
from(A, B)   --> state([A,_,B,_,_,_]).
animal(A, B) --> state([A,_,_,B,_,_]).
drink(A, B)  --> state([A,_,_,_,B,_]).
smoke(A, B)  --> state([A,_,_,_,_,B]).

X = Y --> {
    X=..[Fx|Ax], Y=..[Fy|Ay],
    Xs=..[Fx,S|Ax], Ys=..[Fy,S|Ay]
}, call(Xs), call(Ys).

next_to(X, Y) --> {1 is abs(X-Y)}.