I would like to change the font of the alerted text in my beamer, I want it to be in bold, in both text and math mode. I tried using boldmath but it doesn't work :
\begin{frame}{Test}
\setbeamercovered{invisible}
\setbeamercolor{alerted text}{fg=vertf}
\setbeamerfont{alerted text}{family=\sffamily, series=\bfseries\boldmath}
$$\alert<2>{x} + \alert<3>{y} + \alert<4>{z}$$
\begin{itemize}
\item <2-| alert@2>x
\item <3-| alert@3>y
\item <4-| alert@4>z
\end{itemize}
\end{frame}
You could work around the problem with something like this:
\documentclass{beamer}
\setbeamercovered{invisible}
\setbeamercolor{alerted text}{fg=green}
\setbeamerfont{alerted text}{series=\bfseries\boldmath}
\renewcommand<>{\alert}[1]{%
\ifmmode\text{%
\begin{alertenv}#2\relax$#1$\end{alertenv}%
}%
\else%
\begin{alertenv}#2\relax#1\end{alertenv}%
\fi%
}
\begin{document}
\begin{frame}
\frametitle{Test}
\[
\alert<2>{x} + \alert<3>{y} + \alert<4>{z}
\]
\begin{itemize}
\item <2-| alert@2>x
\item <3-| alert@3>y
\item <4-| alert@4>z
\end{itemize}
\end{frame}
\end{document}