\item \lect \dpllDescription{negative}
\begin{dpllCNFInput}
    \item $\{\lnot a,\lnot b\}$
    \item $\{a,c\}$
    \item $\{b,\lnot c\}$
    \item $\{\lnot b,d\}$
    \item $\{\lnot c,\lnot d\}$
    \item $\{c,e\}$
    \item $\{c,\lnot e\}$
\end{dpllCNFInput}