\item \ifassignmentsheet \points{5} \fi
  Use the lazy encoding approach to check whether the formula $\varphi$ in $\EUF$ is satisfiable.
  \begin{align*}
  \varphi =& (\clause{(a=x); (a=y); (x=y)})\land (\clause{\lnot (a=x); (a=y)})~\land \\
           & (\clause{\lnot (a=y); (x=y)})\land (\clause{(x=y); (z=a)})~\land \\
           & (\clause{\lnot (x=y); (b=z)})\land (\clause{\lnot (z=a); \lnot (b=z)})
  \end{align*}