Idk, `o3-mini-high` was able to pop this Prolog code out in about 20 seconds:
solve(WaterDrinker, ZebraOwner) :-
% H01: Five houses with positions 1..5.
Houses = [ house(1, _, norwegian, _, _, _), % H10: Norwegian lives in the first house.
house(2, blue, _, _, _, _), % H15: Since the Norwegian lives next to the blue house,
house(3, _, _, milk, _, _), % and house1 is Norwegian, house2 must be blue.
house(4, _, _, _, _, _),
house(5, _, _, _, _, _) ],
% H02: The Englishman lives in the red house.
member(house(_, red, englishman, _, _, _), Houses),
% H03: The Spaniard owns the dog.
member(house(_, _, spaniard, _, dog, _), Houses),
% H04: Coffee is drunk in the green house.
member(house(_, green, _, coffee, _, _), Houses),
% H05: The Ukrainian drinks tea.
member(house(_, _, ukrainian, tea, _, _), Houses),
% H06: The green house is immediately to the right of the ivory house.
right_of(house(_, green, _, _, _, _), house(_, ivory, _, _, _, _), Houses),
% H07: The Old Gold smoker owns snails.
member(house(_, _, _, _, snails, old_gold), Houses),
% H08: Kools are smoked in the yellow house.
member(house(_, yellow, _, _, _, kools), Houses),
% H11: The man who smokes Chesterfields lives in the house next to the man with the fox.
next_to(house(_, _, _, _, _, chesterfields), house(_, _, _, _, fox, _), Houses),
% H12: Kools are smoked in a house next to the house where the horse is kept.
next_to(house(_, _, _, _, horse, _), house(_, _, _, _, _, kools), Houses),
% H13: The Lucky Strike smoker drinks orange juice.
member(house(_, _, _, orange_juice, _, lucky_strike), Houses),
% H14: The Japanese smokes Parliaments.
member(house(_, _, japanese, _, _, parliaments), Houses),
% (H09 is built in: Milk is drunk in the middle house, i.e. house3.)
% Finally, find out:
% Q1: Who drinks water?
member(house(_, _, WaterDrinker, water, _, _), Houses),
% Q2: Who owns the zebra?
member(house(_, _, ZebraOwner, _, zebra, _), Houses).
right_of(Right, Left, Houses) :-
nextto(Left, Right, Houses).
next_to(X, Y, Houses) :-
nextto(X, Y, Houses);
nextto(Y, X, Houses).
Seems ok to me.
?- solve(WaterDrinker, ZebraOwner).
WaterDrinker = norwegian,
ZebraOwner = japanese .
