\begin{frame}
  \frametitle{Modalities}

  \begin{goal}{}
    Modal logic introduces \emph{modalities}
    \begin{itemize}
      \item box $\all$
      \item diamond $\some$
      \smallskip
    \end{itemize}
  \end{goal}
  \pause
  
  \vspace{-2ex}
  \begin{eqnarray*}
    \DARKRED{\all} & &\DARKGREEN{\some}\\
    \DARKRED{\mbox{\em{``Box''}}} && \DARKGREEN{\mbox{\em``Diamond''}}\\
    \hline
    \\[-.5ex]
    \DARKRED{sure}  && \DARKGREEN{possibly} \\
    \DARKRED{always}  && \DARKGREEN{sometimes} \\
    \DARKRED{has\;to\;be}  && \DARKGREEN{maybe} \\
    \DARKRED{knows}  && \DARKGREEN{believes\;is\;possible}  \\
    \DARKRED{guaranteed\;result}  && \DARKGREEN{possible\;result} 
  \end{eqnarray*}
\end{frame}