% File ltlfonts-quickstart.ltx
\documentclass{article}

\usepackage{ltlfonts}

\begin{document}
LTLFonts provides some nice boxes and circles. For example:

$\LTLsquare \LTLdiamond \LTLcircle a$, $\LTLcircleminus
\LTLdiamondminus \LTLsquareminus \LTLcircletilde b$, $\LTLsquarehat
\LTLdiamondminushat c$
\end{document}