p(X).
q(f(X)) :- r(X).
r(g(X)) :- s(X).
s(h(X)) :- p(X).

?- p(a).
?- p(X).
?- p(Y).
?- q(Z).


--- Ergebnis: --------------------------------------------------------

?- p(a).

Resolution 1: Yes.

Resolution 2: No.


?- p(X{0}).

Resolution 1: Yes.
X = X{0}

Resolution 2: No.


?- p(Y{0}).

Resolution 1: Yes.
Y = Y{0}

Resolution 2: No.


?- q(Z{0}).

Resolution 1: Yes.
Z = f(g(h(X{3})))

Resolution 2: No.