# Multline and qedhere

One of the proofs in my paper ends with a multi-line equation. Unfortunately, when I put the QED sign at the end via the \qedhere command, it does not end up at the end of the line like the other QED signs (it also throws a warning that \qedhere may not work correctly). The difference is not big, but it's kind of annoying. How to make it right?

EDIT: now I see that a similar question has already been asked, but that was five years ago (and the suggested workaround does not seem to work). Has nothing changed?

MWE:

\documentclass{amsart}

\begin{document}
\begin{proof}
This is the first proof.
\end{proof}

\begin{proof}
This is another proof.
\begin{multline}
6\cdot 9=\\
42\qedhere
\end{multline}
\end{proof}
\end{document}


• I'm afraid this is a known bug of amsthm. – egreg Jun 1 '18 at 13:33
• @egreg: I see. Still, maybe one can work around it? – tomasz Jun 1 '18 at 13:39
• Strangely, your code doesn't have this problem on my system. – Bernard Jun 1 '18 at 14:19
• @Bernard: well, on my system the result is this: imgur.com/a/8AzSgYv – tomasz Jun 1 '18 at 14:29
• @tomasz -- i've taken the liberty of adding the image. – barbara beeton Jun 1 '18 at 14:45

this isn't ideal, but if you're willing to put up with the vertically centered equation number and qed box, and the narrowed alignment of the display math, it at least doesn't complain.

\documentclass{amsart}
\usepackage{mathtools}

\begin{document}
\begin{proof}
This is the first proof.
\end{proof}

\begin{proof}
This is another proof.
$$\begin{multlined} 6\cdot 9=\\ 42 \end{multlined} \qedhere$$
\end{proof}
\end{document}


• I don't really care about the equation number (I don't really do numbered equations in the first place). The fact that the qed box is centered is a bit annoying, but better than having it horizontally misaligned. While indeed not perfect, this seems good enough. Thanks! – tomasz Jun 1 '18 at 14:08