\item Use the DPLL algorithm (\emph{without} BCP, PL and clause learning) to determine whether or not the set of clauses given is satisfiable. Decide variables in alphabetical order starting with the \textit{negative} phase. If the set of clauses resulted in \texttt{SAT}, give a satisfying model.

\begin{dpllCNFInput}
  \item $(\lnot a \lor \lnot b)$
  \item $(c \lor \lnot d)$
  \item $(a \lor \lnot b)$
  \item $(c \lor d)$
\end{dpllCNFInput}
