# Unindented proof in amsbook

I am using the proof environment in amsbook. Unlike amsart, the proof is automatically indented. Is there a way of cancelling the indentation?

\documentclass{amsbook}
\begin{document}
\noindent This is a non-indented sentence.
\begin{proof}
This is a proof.
\end{proof}
\end{document}


Say

\usepackage{etoolbox}
\expandafter\patchcmd\csname\string\proof\endcsname
{\normalparindent}{0pt }{}{}


which is equivalent (but shorter) to redefining the proof environment as follows

\makeatletter
\renewenvironment{proof}[1][\proofname]{\par
\pushQED{\qed}%
\normalfont \topsep6\p@\@plus6\p@\relax
\trivlist
\itemindent\z@ % original has \normalparindent
\item[\hskip\labelsep
\scshape
}{%
\popQED\endtrivlist\@endpefalse
}
\makeatother

• The first block somehow doesn't work for me, but the second does exactly what I want! Thanks! Sep 27 '11 at 16:06

amsbook defines \normalparindent (18 pt) and uses it for \itemindent within the proof environment. Here's a redefinition which avoids that, I simply redefined and commented one line out:

\makeatletter
\renewenvironment{proof}[1][\proofname]{\par
\pushQED{\qed}%
\normalfont \topsep6\p@\@plus6\p@\relax
\trivlist
%\itemindent\normalparindent
\item[\hskip\labelsep
\scshape