First paragraph of section becomes indented after setting \setbeforesecskip (memoir class)

Question

I am trying to adapt my thesis draft to the format specifications of my university, which mandates among other things the number of line skips before and after section and subsection titles. I am using the memoir class and the following code to enforce the line skip rules:

\setbeforesecskip{2em}
\setbeforesubsecskip{2em}
\setbeforesubsubsecskip{2em}
\setaftersecskip{1em}
\setaftersubsecskip{1em}
\setaftersubsubsecskip{1em}

My problem is that when I add the above lines to the document preamble, the first paragraph after each section and subsection is indented. If I remove them, the behavior reverts back to the default of no indentation for the first paragraph, which I want.

Could you please help with this puzzling behavior?

Answer 1

memoir uses a modified version of the \@startsection command, but one puzzling aspect of this command is nevertheless present. Quoting from the LaTeX 2e Sources, p. 283:

beforeskip: Absolute value = skip to leave above the heading. If negative, then paragraph indent of text following heading is suppressed.

In other words, add a minus sign to the argument of your \setbeforeXskip commands.

\documentclass{memoir}

\setbeforesecskip{-2em}
\setbeforesubsecskip{-2em}
\setbeforesubsubsecskip{-2em}
\setaftersecskip{1em}
\setaftersubsecskip{1em}
\setaftersubsubsecskip{1em}

\begin{document}

\chapter{bla}

Some text.

\section{blubb}

Some text.

\subsection{foo}

Some text.

\subsubsection{bar}

Some text.

\end{document}