gistfile1.pl

father(naoyuki, hyogo).
father(saburo, naoyuki).
father(saburo, shinji).
father(yoshihisa, hisako).
mother(hisako, hyogo).
mother(yoko, naoyuki).
mother(yoko, shinji).
mother(nobuko, hisako).

parent(P, C) :- father(P, C).
parent(P, C) :- mother(P, C).

grandfather(GF, C) :- parent(P, C), father(GF, P).
grandmother(GF, C) :- parent(P, C), mother(GF, P).

grandparent(GP, C) :- grandfather(GP, C).
grandparent(GP, C) :- grandmother(GP, C).

child(C, P) :- parent(P, C).

grandchild(C, G) :- grandparent(G, C).

sibling(X, Y) :- parent(P, X), parent(P, Y).

son(S, P) :- parent(P, S).

uncle(U, C) :- parent(P, C), brother(P, U), not(P = U).

ancestor(A, C) :- parent(A, C).
ancestor(A, C) :- parent(P, C), ancestor(A, P).

descendant(D, P) :- child(D, P).
descendant(D, P) :- child(C, P), descendant(D, C).