[Tex/LaTex] Special sign \pounds changed to dollar sign in alignment surrounding


I am writing a beamer and use

\pounds^i_M   etc.

on a slide. The pounds sign then changes to a dollar sign. How do I write to get the pounds sign?

\setlength{\unitlength} {1mm}


\frame { \maketitle}

\frame{ \frametitle{Prescriptions of \pounds \ I: Classical logical maxims} \begin{align*}
\pounds^i_M & \qquad A\rightarrow (B\rightarrow A)

Best Answer

I have also this problem when using the fonts Beamer loads by default (Computer Modern sans serif). If I use their Latin Modern equivalent, it works fine:

\begin{align*} \pounds^i_M  \end{align*}

enter image description here