I'm getting the error No counter 'theorem' defined Heres my code below


\newcommand{\package}[1]{\textbf{#1}} % package names in bold text
\newcommand{\cmmd}[1]{\textbackslash\texttt{#1}} % command name in tt font 



\newcommand{\real}{\mathbb{R}} %IMPORTANT

  • Your example is not compilable, but you don't have the theorem environment defined. Quick workaround: \newcounter{theorem}
    – user31729
    Apr 10, 2017 at 15:43
  • 2
    The statement \newtheorem{thm}[theorem]{Theorem} doesn't make much sense. Use \newtheorem{theorem}{Theorem} instead -- and place this instruction before \newtheorem{lem}[theorem]{Lemma}.
    – Mico
    Apr 10, 2017 at 16:01
  • you might benefit from reading the amsthm package documentation -- texdoc amdthm. the use of counters is explained pretty clearly there. Apr 10, 2017 at 20:05

1 Answer 1


Rearrange the \newtheorems as follows, and use [thm] instead of [theorem].


This means that the thm environment will use a counter thm, and all the other theorem-like environments will use the same counter thm.

Here is a complete example.

enter image description here

  Some theorem.
  Some lemma.
  A conjecture.
  • I'm having trouble getting this to work still getting environment lemma undefined btw what difference does changing the theorem to thm do? \documentclass[11pt]{article} \usepackage{amsthm} %\newtheorem{theorem}{Theorem} \newtheorem{thm}{Theorem} \newtheorem{lem}[thm]{lemma} %\newtheorem{theorem}{Theorem} \begin{document} %\begin{theorem} %adfasdfadsf %\end{theorem} \begin{lemma} adasd \end{lemma} \end{document}
    – Hao S
    Apr 10, 2017 at 16:13
  • @HaoSun I've added an example. Check whether it works for you.
    – gernot
    Apr 10, 2017 at 16:23
  • @HaoSun, you can refer to the counter created by the first \newtheorem{}{} you use. \newtheorem{thm}{Theorem} creates a counter named thm.
    – Sigur
    Apr 10, 2017 at 16:27
  • Okay I see lem is the thing your suppose to enter not lemma I didn't really understand the code thanks everyone
    – Hao S
    Apr 10, 2017 at 16:47

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