% Some examples of unifications: do them first by hand! (following the
% unification algorithm) and check them after in the Prolog top level

% p(X,f(b)) = p(a,Y).

% p(X,f(Y)) = p(a,g(b)).

% p(X,X) = p(f(Z),f(W)).

% p(X,f(Y)) = p(Z,X).

% p(X,f(X)) = p(Z,Z).

% With this last one try also:
% ?- use_module(library(iso_misc)).
% ?- unify_with_occurs_check(p(X,f(X)),p(Z,Z)).
% Can you explain the difference?