11

I have a document with a lemma (using amsthm), like so:

\begin{lem} \label{mylemma}
  % ...
\end{lem}

The proof of this lemma can be found in the appendix (see section \ref{sec:proof_of_mylemma}).

I now place a copy of the lemma in the appendix, with proof included:

\section{Appendix}

\section{Proof of lemma \ref{mylemma}} \label{sec:proof_of_my_lemma}

\begin{lem}
  % ...
\end{lem}

\begin{proof}
  % ...
\end{proof}

The problem is that the second copy of my lemma has a new number. How can I renumber this lemma to mimick the number of mylemma?

Thanks!

gdiazc
  • 345

2 Answers2

19

You can use the restatable environment provided by the thmtools package:

\documentclass{article}
\usepackage{amsthm}
\usepackage{thmtools,thm-restate}

\newtheorem{lem}{Lemma}

\begin{document}

\begin{restatable}{lem}{primelemma}
\label{mylemma}
Let $p$ be a prime number, and assume $p$ divides the product of two integers $a$ and $b$. Then $p$ divides $a$ or $p$ divides $b$.
\end{restatable}

\section{Proof of lemma~\ref{mylemma}} 
\primelemma*

\end{document}

enter image description here

Gonzalo Medina
  • 505,128
  • What about the opposite: cite the lemma before? For example, cite on Introduction the Lema 1.2 with the same numbering. – Sigur Feb 04 '14 at 14:03
  • 2
    @Sigur in that case, use the starred version restatable* in the Introduction and the un-starred \primelemma further on in the document. – Gonzalo Medina Feb 04 '14 at 16:57
1

This really should be a comment rather than an answer, but I do not have sufficient reputation to comment. Hopefully someone will find this helpful and avoid some headache. You cannot use a number at the end of the reference. The following will fail:

documentclass{article}
\usepackage{amsthm}
\usepackage{thmtools,thm-restate}

\newtheorem{lem}{Lemma}


\begin{document}


\begin{restatable}{lem}{mylemma1}
\label{mylemma}
I claim that $1+1=2$.
\end{restatable}


\section{Proof of lemma~\ref{mylemma}} 
\mylemma1*


\end{document}

but the following will compile properly

documentclass{article}
\usepackage{amsthm}
\usepackage{thmtools,thm-restate}

\newtheorem{lem}{Lemma}


\begin{document}


\begin{restatable}{lem}{mylemmaone}
\label{mylemma}
I claim that $1+1=2$.
\end{restatable}


\section{Proof of lemma~\ref{mylemma}} 
\mylemmaone*


\end{document}
daydaybroskii
  • 11