No indentation of first line in amsbook chapter

Question

How do I have to change amsbook.cls such that the first line of a new chapter is not indented?

Answer 1

The first indent after chapters and sections is controlled by \if@afterindent. Class amsbook sets it to true. The following example prevents this setting in the same way as package indentfirst does the opposite:

\documentclass{amsbook}
\usepackage{lipsum}
\makeatletter
\let\@afterindenttrue\@afterindentfalse
\makeatother
\begin{document}
\chapter{Chapter title}
\lipsum[1-2]
\end{document}