\item \ifassignmentsheet \points{3}
  \dpllDescriptionAssignmentSheet
\else \prac
  \dpllDescription{negative}
\fi

\begin{dpllCNFInput}
    \item $\{a, b\}$
    \item $\{\neg b, c\}$
    \item $\{\neg a, \neg c\}$
    \item $\{b, c\}$
    \item $\{a, \neg b\}$
    \item $\{\neg b, \neg c\}$
\end{dpllCNFInput}