\item \ifassignmentsheet \points{5} \fi
  Use the lazy encoding approach to check whether the formula $\varphi$ in $\EUF$ is satisfiable.
  $$\varphi := (x = y) \land (y = f(y)) \land (y \neq f(x)) \land (z = f(z)) \land (f(z) = f(x)) $$