3

I am using the amsthm package and get a blank square like $\Square$ at the end of proofs. How can I redefine to get the black Halmos tombstone $\Blacksquare$ instead?

I want the symbol to be right aligned, but it would be useful if I were to be able to switch off the right-alignment.

7

Redefine \qedsymbol:

\documentclass{article}
\usepackage{amsthm}
\usepackage{amssymb}

\renewcommand\qedsymbol{$\blacksquare$}

\begin{document}

\begin{proof}
A test text
\end{proof}

\end{document}

enter image description here

I wouldn't recommend to switch off right alignment for the end-mark (it's not standard, so readers might miss the end-mark and quite franckly, it looks ugly), but you could do something like this:

\documentclass{article}
\usepackage{amsthm}
\usepackage{amssymb}

\renewcommand\qedsymbol{$\blacksquare$}
\makeatletter
\renewenvironment{proof}[1][\proofname]{\par
  \normalfont \topsep6\p@\@plus6\p@\relax
  \trivlist
  \item[\hskip\labelsep
        \itshape
    #1\@addpunct{.}]\ignorespaces
}{%
  \nolinebreak\qedsymbol\endtrivlist\@endpefalse
}
\makeatother

\begin{document}

\begin{proof}
A test text some more text and some more text and some more text and
\end{proof}

\end{document}

enter image description here

As barbara beeton mentions in her comment, it might be desired to turn off right alignment on a per-case basis; in this case, it's enough to locally redefine \qedsymbol to be empty and then add the desired symbol at the end (taking some care to prevent undesired line breaks); something along these lines:

\documentclass{article}
\usepackage{amsthm}
\usepackage{amssymb}

\renewcommand\qedsymbol{$\blacksquare$}
\newcommand\placeqed{\nobreak\enspace$\blacksquare$}

\begin{document}

\begin{proof}
A test text some more text and some more text and some more text and
\end{proof}

\begin{proof}
\renewcommand\qedsymbol{}
A test text some more text and some more text and some more text and\placeqed
\end{proof}

\end{document}

enter image description here

| improve this answer | |
  • That is nice! Do you know how i may turn off the rught alignment? – Sapiens Jul 25 '15 at 2:10
  • 2
    @FrodeBjørdal I updated my answer with a better redefinition. However, I insist, I wouldn't recommend this. – Gonzalo Medina Jul 25 '15 at 2:19
  • to get rid of the automatic right-aligned symbol, it's sufficient to \renewcommand{\qedsymbol}{}. then the desired symbol can simply be inserted at the end of the text with \nobreak\hspace{<dimen>}\<symbolname>; i specified \nobreak because such a symbol is likely to get overlooked on a line by itself (and it doesn't look very good either). the redefinition of the symbol will persist only for the current proof; this enables both formats to be used, while redefining proof limits your options. – barbara beeton Jul 25 '15 at 9:38
  • @barbarabeeton Yes, it's better to have both options. I'll add your suggestion to my answer. Thanks. – Gonzalo Medina Jul 25 '15 at 13:34

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.