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\begin{document}
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\section{Basic math}
\[ a + b + c - d + e \]
\[ a + b c - d  e \]
\[ a b c / d e \]
\[ a \times b \times c / d \times e \]

\paragraph{N-ary special cases}
\[ a \times b \times c \times d \]
\[ (a \times b) \times (c \times d) \]
\[ ((a \times b) \times (c \times d)) \]

\[ a / b / c \]
\[ \frac{a}{b} / c \]
\[ a / \frac{b}{c} \]

\[ a \times \fbox{$b \times c$}\]
\section{Evaluate At}
\[  a |_\infty \]
\[ a b |_{a=0} c d |_{c=0} e \]

\section{Absolute values}
\[  |a| \]
\[ ||a|| \]
\[  |a |_\infty \]
\[  |a + b| \]
\[  |a - |b|| \]

\section{Failures w/o Backtracking}
\[  ||a| - |b|| \]
\[ ||a|-b| \]
\[  |a | b |_\infty \]
% This one's too weird
%\[  |a b |_\infty c | \]

\end{document}
