The abstract environment changes the \linewidth for the whole document

Question

In the article class, it seems that using the abstract environment has an effect to the rest of the document. More precisely, it seems that it redefines the \linewidth, which equals \textwidth without abstract, is smaller with the abstract. My feeling is that \linewidth is redefined for the abstract environment, but the value is not reseted at the end of the abstract.

Here is a minimal example:

\documentclass{article}
\begin{document}
\abstract{This is an abstract. This is an abstract.}\bigskip

This is text. This is text. This is text. This is text. This is text. This is text.\\ 
\rule{\textwidth}{3em}
\rule{\linewidth}{3em}
\end{document}

The output is not the same if you comment the \abstract line or not.

Do you have the same problem as I do when you compile (if not, I will upload some PDF files to show)? Is this a (known) bug in LaTeX2e? How can we circumvent the problem?

Note: I compile with the pdflatex command, and I use pdfTeX, Version 3.1415926-1.40.10 (TeX Live 2009/Debian).

Answer 1

abstract is an environment and should be used as such. And \linewidth is smaller than \textwidth within abstract because abstract (without article's titlepage class option) is based on the quotation environment which adds left-hand and right-hand indentation.

\documentclass{article}

\begin{document}

\begin{abstract}
This is an abstract. This is an abstract.
\end{abstract}

\bigskip

This is text. This is text. This is text. This is text. This is text. This is text.\\ 
\rule{\textwidth}{3em}
\rule{\linewidth}{3em}

\end{document}