Alternative theorem numbering separator

Question

I'm using amsthm and I want to have this numbering format for my theorems: Chapter-Section-Theorem

The main difference with the default version is the use of "-" instead of "." .

Can I do this by defining a new theoremstyle?

Answer 1

Something like this?

\documentclass{report} % document class that features 'chapter' sectioning level
\usepackage{amsthm}
\theoremstyle{plain}
\newtheorem{thm}{Theorem}[section]
\renewcommand\thethm{\thechapter-\arabic{section}-\arabic{thm}}
\begin{document}

\setcounter{chapter}{2}
\setcounter{section}{3}
\begin{thm} aaa \label{thm:aaa} \end{thm}

A cross-reference to Theorem \ref{thm:aaa}.

\end{document}