# Assigning Theorem number from ref

I would like to know if there is an easy way to the following.

I have a statement in later part of an article, say Theorem G with \label{Thm:G}. In the introduction I would like to state this theorem as

Theorem G
2 + 2 = 4.

Is this possible?

I would like to have Theorem 2.1 in the Intro section.

%---- MWE
\documentclass{article}
\usepackage{amsthm}
\newtheorem{thm}{Theorem}[section]

\begin{document}
\section{Intro}

\section{body}
\begin{thm}\label{theorem G}
$2+2 = 4$.
\end{thm}

\end{document}

• To be honest i don't understand the question's purpose, but the answers below show us a point of view completely different. – skpblack Jul 3 '14 at 6:37
• @skpblack: The answer by Werner is what I was looking for. – Youngsu Jul 3 '14 at 8:58

A quick-and-easy way of obtaining this is to create a mock "duplicate" theorem environment which you never really use in its entirety. Instead, you adjust the counter representation to adopt that of a reference to the theorem you're after:

\documentclass{article}
\usepackage{amsthm}
\newtheorem{thm}{Theorem}[section]
\newtheorem{thmB}{Theorem}% Dummy theorem

\begin{document}
\section{Intro}

\renewcommand{\thethmB}{\ref{thm:G}}
\begin{thmB}
$2+2 = 4$.
\end{thmB}

\section{body}
\begin{thm}\label{thm:G}
$2+2 = 4$.
\end{thm}

\end{document}


The advantage here is that you could use multiple different references throughout your document, merely changing \thethmB to your liking.

• Werner: I have one question. I was not able to understand the renewcommand. What does "\thmthmb" do? – Youngsu Jul 3 '14 at 8:57
• @Youngsu: When you create \newtheorem{thmB}{Theorem}, it creates a counter thmB. \thethmB is the printing mechanism for this counter, which defaults to \arabic{thmB} (note that this use of \the is different from what is described in The \the command). So, \thethmB is used or equivalent to <num> when printing Theorem <num>. All I've done is replaced the usual \arabic{thmB} with a reference. – Werner Jul 3 '14 at 14:01