# Controlling numbering of theorems in Beamer

I have a theorem that is too long for one frame. As \allowframebreaks does not work within the \theorem environment, I am trying to find a workaround. I can simply end the theorem environment on one frame and begin a new theorem environment on the next, thus splitting my theorem into two. However, this upsets the numbering system. Is it possible to manually change the theorem count so that I can re-use the last theorem number?

\documentclass{beamer}
\usetheme{CambridgeUS}
\setbeamertemplate{theorems}[numbered]

\begin{document}

\begin{frame}
\begin{theorem}
This is the beginning of Theorem 1.
\end{theorem}
\end{frame}

\begin{frame}
\begin{theorem}[cont.]
This is the continuation of Theorem 1.
\end{theorem}
\end{frame}

\begin{frame}
\begin{theorem}
This is Theorem 2.
\end{theorem}
\end{frame}

\end{document}


Just step the counter back before starting the continuation:

\documentclass{beamer}% http://ctan.org/pkg/beamer
\usetheme{CambridgeUS}
\setbeamertemplate{theorems}[numbered]

\begin{document}

\begin{frame}
\begin{theorem}
This is the beginning of Theorem 1.
\end{theorem}
\end{frame}

\begin{frame}
\begin{theorem}[cont.]
This is the continuation of Theorem 1.
\end{theorem}
\end{frame}

\begin{frame}
\begin{theorem}
This is Theorem 2.
\end{theorem}
\end{frame}

\end{document}