Getting rid of indentation of first paragraph in AMS classes

Question

Consider the following MWE:

\documentclass{amsbook}
\usepackage{lipsum}

\begin{document}
\chapter{Test}
\section{Test}
\lipsum
\end{document}

Then a partial output is given by

Thus the AMS class automatically indents the first line of a paragraph after a section (or more generally, after a heading). However, as far as I read, the standard convention is to not indent the first line of a paragraph after a heading. How can I achieve this in this specific class? Moreover, why is this default in the AMS class?

Do you mean the first line of any paragraph or only the first line of the first paragraph after a heading? It is not at all unusual that the first lines of subsequent paragraphs are indented, but for the first paragraph you can either add the indentation or drop it. Both conventions are in use. I'd have thought that would be a matter of style and taste. — moewe, Oct 31 '18 at 16:07
@moewe Sorry, added a clarification. I mean, I would like to not indent the first line after a heading. — TheGeekGreek, Oct 31 '18 at 16:08

moewe · Accepted Answer · 2018-10-31T16:30:14.270

Borrowing from the excellent indentfirst but reversing the logic, you can try

\documentclass{amsbook}
\usepackage{lipsum}

\makeatletter
\let\@afterindenttrue\@afterindentfalse
\@afterindentfalse
\makeatother

\begin{document}
\chapter{Test}
\section{Test}
\lipsum
\end{document}

There seems to be no consensus on whether or not the first paragraph after a heading should start indented or not, see No indent in the first paragraph in a section?, https://writing.stackexchange.com/q/3152 or https://practicaltypography.com/first-line-indents.html:

A first-line indent on the first paragraph of any text is optional, because it’s obvious where the paragraph starts.

I guess you could argue for both sides. But it does not seem to be an issue that sparks a lot of controversies.

The LaTeX standard classes don't start the first paragraph indented, but indentfirst enables this behaviour for people who want this. Apparently someone thought that feature was worth the ordeal of writing a package for it. Apparently the AMS agrees and also indents the first paragraph.

@TheGeekGreek If you want to know why the AMS start with a paragraph indent, you try and can ask barbara beeton, perhaps she happens to know who decided this. — moewe, Oct 31 '18 at 16:20

score 2 · Answer 2 · answered Oct 31 '18 at 16:34

You can patch \chapter to issue \@afterindentfalse instead of \@afterindenttrue.

Also \section should be patched so its fourth argument has a negative value instead of positive.

\documentclass{amsbook}
\usepackage{etoolbox}
\usepackage{lipsum}

\makeatletter
\patchcmd{\chapter}{\@afterindenttrue}{\@afterindentfalse}{}{}
\patchcmd{\section}
  {.7\linespacing\@plus\linespacing}
  {-.7\linespacing\@plus-\linespacing}
  {}{}
\makeatother

\begin{document}
\chapter{Test}

\lipsum[3]

\section{Test}

\lipsum[4]

\subsection{Test}

\lipsum[2]

\end{document}

Getting rid of indentation of first paragraph in AMS classes

2 Answers2