Why is this footnote displayed four times?

Question

Here is my code:

\documentclass{beamer}
\begin{document}
\begin{frame}
\begin{definition}[Clopen Set]
 $A$ is a clopen set iff
    \begin{equation}
        A \in \mathcal{A}&amp;\neg A \in \mathcal{A}\text{\footnote{Equivalently, $A \in\mathcal{A} \cap \neg \mathcal{A}$}}
    \end{equation}

\end{definition}
\end{frame}
\end{document}

However, the slide looks like this:

Please, help :(

Off topic, but it's probably better to avoid putting a footnote inside the equation in the first place. Here it looks like you're talking about an element of a set called A^1, and I'm sure that would confuse me. — N. Virgo, Dec 26 '22 at 02:36

score 3 · Accepted Answer · answered Dec 25 '22 at 18:37

This way, it appears only once:

\documentclass{beamer}
\begin{document}
\begin{frame}
    \begin{definition}[Clopen Set]
        $A$ is a clopen set iff
        \begin{equation*}
            A \in \mathcal{A}\&amp;\neg A \in \mathcal{A}\footnote{\text{Equivalently, $A \in\mathcal{A} \cap \neg \mathcal{A}$}}
        \end{equation*}         
    \end{definition}
\end{frame}


\end{document}

score 0 · Answer 2 · answered Dec 26 '22 at 10:33

There's no reason for using \text, neither around \footnote nor inside it.

\documentclass{beamer}
\begin{document}
\begin{frame}
\begin{definition}[Clopen Set]
 $A$ is a clopen set iff
    \begin{equation}
        A \in \mathcal{A}\mathrel{&amp;}\neg A \in \mathcal{A}
        \footnote{Equivalently, $A \in\mathcal{A} \cap \neg \mathcal{A}$}
    \end{equation}
\end{definition}
\end{frame}
\end{document}

Note \mathrel{\&} in order to get better spacing.

But why a footnote?

\documentclass{beamer}
\begin{document}
\begin{frame}
\begin{definition}[Clopen Set]
 $A$ is a clopen set iff
    \begin{equation}
        A \in \mathcal{A}\mathrel{&amp;}\neg A \in \mathcal{A}
        \footnote{Equivalently, $A \in\mathcal{A} \cap \neg \mathcal{A}$}
    \end{equation}
\end{definition}
\end{frame}
\begin{frame}
\begin{definition}[Clopen Set]
 $A$ is a clopen set iff
    \begin{equation}
        A \in \mathcal{A}\mathrel{&amp;}\neg A \in \mathcal{A}
    \end{equation}
Equivalently, $A \in\mathcal{A} \cap \neg \mathcal{A}$
\end{definition}
\end{frame}
\end{document}

John Kormylo · Answer 3 · 2022-12-26T17:25:49.313

Just for fun:

\documentclass{beamer}
\begin{document}
\begin{frame}
\begin{definition}[Clopen Set]
 $A$ is a clopen set iff
    \begin{equation}
        A \in \mathcal{A}&amp;\neg A \in \mathcal{A}\tag{\footnote{Equivalently, $A \in\mathcal{A} \cap \neg \mathcal{A}$}}
    \end{equation}
 or
    \begin{equation}
        A \in \mathcal{A}&amp;\neg A \in \mathcal{A}\tag{Equivalently, $A \in\mathcal{A} \cap \neg \mathcal{A}$}
    \end{equation} 
 or
    \begin{align}
        A \in \mathcal{A}&amp;\neg A \in \mathcal{A} && \text{Equivalently, } A \in\mathcal{A} \cap \neg \mathcal{A}
    \end{align} 
\end{definition}
\end{frame}
\end{document}

Why is this footnote displayed four times?

3 Answers3