\renewcommand{\arraystretch}{1.2}
\begin{tabular}{@{}l|l@{}}\hline
\multicolumn{1}{c|}{$\Box \phi$} &\multicolumn{1}{c}{$\Dia \phi$}
\\\hline
It is necessarily true that $\phi$ & It is possibly true that $\phi$\\
It will always be true that $\phi$ & Sometime in the future $\phi$\\
It ought to be that $\phi$ & It is permitted to be that $\phi$\\
Agent Q believes that $\phi$ & $\phi$ is consistent with Q's beliefs\\
Agent Q knows that $\phi$ & For all Q knows, $\phi$\\
After any execution of program P, $\phi$ holds & After some execution of P,
$\phi$ holds \\
\hline
\end{tabular}