Here is my MWE: I may not use all of the packages but I put them all just to be safe.: I am using the command \newtcbtheorem with the commands \usepackage{tcolorbox} \tcbuselibrary{theorems} for theorems with the appendixnumberbeamer package to stop frame counting prior appendix in a beamer presentation. The problem is that the Appendix gets labelled section 3 in my MWE here and not section A. So in the title of the theorem in the appendix it states Theorem 3.1 instead of Theorem A.1 (same problem when referencing 3.1 instead of A.1). How do I get theorems in the appendix automatically labelled A.1 and so on with the Appendix section being A rather than Theorem 3.1 of section 3 (as in MWE)?
With MWE
First Section
Theorem 1.1
An important result
Proof uses Stat lemma in 3.1
Appendix
Theorem 3.1
Wanted
First section
Theorem 1.1
An important result
Proof: uses Stat lemma in A.1
Appendix
Theorem A.1
\documentclass[slidetop, 11pt, leqno, english,french]{beamer}
\usepackage[french]{babel}
\usepackage{epsf}
\usepackage{graphicx}
\usepackage{amssymb}
\usepackage{latexsym}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{pifont}
\usepackage{multicol}
\usepackage{xcolor}
\usepackage{textpos}
\usepackage{arydshln}
\usepackage{appendixnumberbeamer}
\usepackage{tcolorbox}
\tcbuselibrary{theorems}
\usepackage{nameref}
\usepackage{hyperref}
\newtcbtheorem[number within=section]{lem}{Lemma}%
{colback=white,colframe=bluegreen,fonttitle=\bfseries}{th}
\newtcbtheorem[number within=section]{thm}{Theorem}%
{colback=white,colframe=bluegreen,fonttitle=\bfseries}{th}
\newtcbtheorem[number within=section]{cor}{Corollary}%
{colback=white,colframe=bluegreen,fonttitle=\bfseries}{th}
\usetheme{Dresden}
\useoutertheme{miniframes}
\definecolor{bluegreen}{rgb}{0.0,0.57,0.5}
\usecolortheme[named=bluegreen]{structure}
\begin{document}
\section{First section}
\begin{frame}
\begin{thm}{}{}
An important result
\end{thm}
Proof: uses the \nameref{th:stat} in \ref{th:stat}
\end{frame}
\section{Second section}
\begin{frame}
\begin{thm}{}{}
An even more important result.
\end{thm}
Proof: Also uses \nameref{th:stat} in \ref{th:stat}
\end{frame}
\appendix
\section{Appendix}
\begin{frame}
\begin{thm}{Stat lemma}{stat}
Statement of the lemma here
\end{thm}
\end{frame}
\end{document}