# How to remove the word “Proof:” from the environment proof?

I am writing a paper and I will prove a theorem in an appendix because the proof is lengthy. When I use the following code,

\documentclass[journal]{IEEEtran}
\usepackage{amssymb, amsmath, amsthm, amsfonts}
\renewcommand*{\proofname}{}

\begin{document}

\appendices
\section{Proof of Theorem \ref{theorem1}}

\begin{proof}
We will use induction to prove this theorem.
\end{proof}
\end{document}


I get the following:

I would like to remove the word "Proof:" from the proof as this is already explained in the name of the appendix.

I have checked the question How to change the word “Proof” in the proof environment?. I tried to change the name to be blank using

\renewcommand*{\proofname}{}


However this does not seem to work.

Use this code

\begin{proof}[\unskip\nopunct]

\end{proof}


A full example:

\documentclass[journal]{IEEEtran}
\usepackage{amssymb, amsmath, amsthm, amsfonts}

\usepackage{showframe} % just to show the margins

\newtheorem{thm}{Theorem}

\begin{document}

\begin{thm}\label{theorem1}
Toasters can fly.
\end{thm}

\appendices
\section{Proof of Theorem \ref{theorem1}}

\begin{proof}[\unskip\nopunct]
We will use induction to prove this theorem.
\end{proof}
\end{document}


• This does not work, it removed the word but not the colon. I am left with : We will use induction .... – BHamza May 30 '14 at 11:23
• Add also \unskip before \nopunct. – egreg May 30 '14 at 11:24
• @BHamza Remove the \renewcommand{\proofname}{} line. – egreg May 30 '14 at 11:24
• @egreg Removed the line, and used the \nopunct it indented the first line to the left, but the colon still exist. Thank you. – BHamza May 30 '14 at 11:26
• I've taken the liberty of adding a MWE in order to show that your suggestion works. Welcome to TeX.SX! Good answer! – egreg May 30 '14 at 11:38

In addition to Karo's answer, which is perfect for IEEEtran.cls version 1.8 released on 2012-12-27 (which is included in up-to-date TeX Live 2012 distributions and in TeX Live 2013 and later), I'll add a workaround for previous versions of the class:

\documentclass[journal]{IEEEtran}
\usepackage{amssymb, amsmath, amsthm, amsfonts}

\usepackage{showframe} % just to show the margins

\newtheorem{thm}{Theorem}

%% define a \killproofname command that works with both
%% IEEEtran.cls version 1.7a or version 1.8
\makeatletter
\@ifclasslater{IEEEtran}{2012/12/26}
{\newcommand{\killproofname}{\unskip\nopunct}}
{\newcommand{\killproofname}[1]{\unskip\aftergroup\ignorespaces\ignorespaces}}
\makeatother

\begin{document}

\begin{thm}\label{theorem1}
Toasters can fly.
\end{thm}

\appendices
\section{Proof of Theorem \ref{theorem1}}

\begin{proof}[\killproofname]
We will use induction to prove this theorem.
\end{proof}
\end{document}


Here's the result compiling with TeX Live 2011, which has IEEEtran.cls version 1.7a, released on 2007/03/05: