% Danish Royal Family

parent( margrethe, frederik).
parent( margrethe, joachim).
parent( henrik, frederik).
parent( henrik, joachim).
parent( mary, christian).
parent( mary, isabella).
parent( frederik, christian).
parent( frederik, isabella).
parent( alexandra, nicolai).
parent( alexandra, felix).
parent( joachim, nicolai).
parent( joachim, felix).
parent( marie, little_henrik).
parent( joachim, little_henrik).



grandparent(X,Z):- parent(X, Y), parent(Y, Z).