# Redefining proof environment

How can I change the \begin{proof} environment so that the word Proof which is displayed in my document isn't italic? I tried changing \proofname, but that only changes the displayed text, not the style.

• Welcome to TeX.SX! It is easier to help you if you add a minimal working example that takes the form \documentclass{...}\usepackage{....}\begin{document}...\end{document}. If possible, it should compile and have the minimum amount of code needed to illustrate your problem. This makes it much easier for people to help you - and much more likely that they will! If you are using the amsthm package then \begin{proof}[\textbf{Proof}]...\end{proof} should put proof in bold.
– user30471
Jun 20, 2015 at 12:36

I assume you're talking about proof as defined by amsthm. The command \itshape is hardwired in the environment's definition.

I suggest patching it so it uses a “generic” command that you can redefine at will:

\usepackage{amsthm}
\usepackage{xpatch}
\xpatchcmd{\proof}{\itshape}{\normalfont\proofnamefont}{}{}



Full example. The \renewcommand is just for testing.

\documentclass{article}

\usepackage{amsthm}
\usepackage{xpatch}
\xpatchcmd{\proof}{\itshape}{\normalfont\proofnamefont}{}{}

\newcommand{\proofnamefont}{}

\begin{document}

\begin{proof}
Obvious, isn't it?
\end{proof}

\renewcommand{\proofnamefont}{\bfseries}

\begin{proof}[Proof in boldface]
Test for boldface and the optional argument.
\end{proof}

\end{document}


Just to clear up things: if you want boldface, the code should be

\documentclass{article}

\usepackage{amsthm}
\usepackage{xpatch}
\xpatchcmd{\proof}{\itshape}{\normalfont\proofnamefont}{}{}

\newcommand{\proofnamefont}{\bfseries}

\begin{document}

\begin{proof}
Obvious, isn't it?
\end{proof}

\end{document}

• @Nicholas I added the amsthm tag, so surely our friend Barbara Beeton will take notice of the feature request. Jun 20, 2015 at 12:47
• request posted, but as a request to add \proofnamefont rather than hard-coded \itshape. in fact, there is a generic request on file to reconsider all hard-coded font settings (except perhaps for italic for the basic theorem environment, although even there i know some people who prefer slanted type). Jun 20, 2015 at 14:39
• @barbarabeeton I have no objection to just \proofnamefont. Jun 20, 2015 at 14:41