# Theorem numbering with sections with LNCS

I'm using the file llncs.cls, downloadable here under "LaTeX2e Proceedings Templates (zip)".

I want to number theorems according to its section, for example Theorem 1.1, Theorem 1.2.

\documentclass[runningheads,a4paper]{llncs}

\newtheorem{thm}{Theorem}[section]

\begin{document}
\section{Section 1}
\begin{thm}
abc
\end{thm}
\begin{thm}
def
\end{thm}
\end{document}


When I do this, what appears instead is Theorem 11 and Theorem 12.

How can I add back the dots?

The llncs class needs the envcountsect option in order to provide the usual behaviour expected from \newtheorem, in addition, llncs uses \spnewtheorem rather than \newtheorem.

\documentclass[envcountsect,runningheads,a4paper]{llncs}

\spnewtheorem{thm}{Theorem}[section]{\bfseries}{\itshape}

\begin{document}
\section{Section foo}
\begin{thm}
abc
\end{thm}
\begin{thm}
def
\end{thm}

\section{Section  foobar}
\begin{thm}
abc
\end{thm}
\begin{thm}
def
\end{thm}

\end{document}


• Theorem in LLNCS should be defined with \spnewtheorem: \spnewtheorem{thm}{Theorem}[section]{\bfseries}{\itshape} – egreg Jun 3 '17 at 23:11