Tombstone symbol in LaTeX

Question

Unicode offers a thin rectangular symbol ▮ instead of the usual square to indicate the end of a proof (See http://en.wikipedia.org/wiki/End_of_proof). Is this by any chance available in LaTeX?

Answer 1

The bbding package offers you \Rectangle, \RectangleBold, and \RectangleThin:

\documentclass{article}
\usepackage{bbding}

\begin{document}
\Rectangle\quad\RectangleBold\quad\RectangleThin
\end{document}

Here they are in action in a proof environment:

\documentclass{article}
\usepackage{amsthm}
\usepackage{bbding}

\begin{document}

\renewcommand\qedsymbol{\Rectangle}
\begin{proof}Test text text text text text text text text text\end{proof}
\renewcommand\qedsymbol{\RectangleBold}
\begin{proof}Test text text text text text text text text text\end{proof}
\renewcommand\qedsymbol{\RectangleThin}
\begin{proof}Test text text text text text text text text text\end{proof}

\end{document}

The pifont package offers two options through \ding{121} and \ding{122}; the marvosym package has \Rectsteel:

\documentclass{article}
\usepackage{amsthm}
\usepackage{pifont}
\usepackage{marvosym}

\begin{document}

% require pifont
\renewcommand\qedsymbol{\ding{121}}
\begin{proof}Test text text text text text text text text text\end{proof}
\renewcommand\qedsymbol{\ding{122}}
\begin{proof}Test text text text text text text text text text\end{proof}
% require marvosym
\renewcommand\qedsymbol{\Rectsteel}
\begin{proof}Test text text text text text text text text text\end{proof}

\end{document}

If you want to, you can scale the symbol using \scalebox from the graphicx package.

Without using additional packages, you can use \rule to define your own symbol:

\documentclass{article}
\usepackage{amsthm}

\newcommand\TombStone{\rule{.5ex}{2ex}}

\begin{document}

\renewcommand\qedsymbol{\TombStone}
\begin{proof}Test text text text text text text text text text\end{proof}

\end{document}