# Indentation for proofs

I'm using amsbook document class and amsthm package. I want the proofs to stand out from the rest of the text by slightly indenting them, i.e. leaving some margins from left and right. How do I do that?

It seems that Margins for proof environment is the same question. But the code doesn't work for me, probably because I'm using amsthm package already.

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May I ask why? It waste space and does not seem to bring anything extra to the understanding of the proof. – daleif Jul 3 '12 at 8:02
It's just an experiment. – john Jul 3 '12 at 8:04

## 2 Answers

You can experiment with this modification of the proof environment:

\documentclass{amsart}
\usepackage{lipsum}
\makeatletter
\renewenvironment{proof}[1][\proofname]{\par
\pushQED{\qed}%
\normalfont \topsep6\p@\@plus6\p@\relax
\list{}{\leftmargin=4em
\rightmargin=\leftmargin
\settowidth{\itemindent}{\itshape#1}%
\labelwidth=\itemindent
% the following line is not needed with amsart, but might be with other classes
\parsep=0pt \listparindent=\parindent
}
\item[\hskip\labelsep
\itshape
#1\@addpunct{.}]\ignorespaces
}{%
\popQED\endlist\@endpefalse
}
\makeatother
\begin{document}
\lipsum[1]

\begin{proof}
\lipsum*[2]
\end{proof}

\lipsum[3]

\end{document}


However it doesn't seem a good idea to me: if the proof is short it's easily recognizable anyway; if it's long, the narrow margin will spoil the page balance.

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How can you make the paragraphs behave normally inside of the indented proof? – Randy Randerson Jun 15 '15 at 20:31
@RandyRanderson They are normally indented, as far as I can see. – egreg Jun 15 '15 at 20:32
Not when you use \documentclass{report}. – Randy Randerson Jun 15 '15 at 20:59
@RandyRanderson Add \parsep=0pt \listparindent=\parindent after \labelwidth=\itemindent, as I did in the code above. – egreg Jun 15 '15 at 21:06
\documentclass{amsbook}
\usepackage{lipsum}
\newenvironment{Proof}[1][Proof]
{\proof[#1]\leftskip=1cm\rightskip=1cm}
{\endproof}

\begin{document}

\begin{proof}
\lipsum[1]
\end{proof}

\begin{Proof}
\lipsum[1]
\end{Proof}

\end{document}


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Did you try with a list (enumerate or itemize) in the Proof environment? – egreg Jul 3 '12 at 10:29