# Double vertical bars alongside statements of theorems

Prof. Hatcher describes a way to produce them in TeX here:

http://www.math.cornell.edu/~hatcher/AT/typography.html

I would like to know if any of you guys knows of a way to generate them in LaTeX.

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This can be easily achieved with the mdframed package; a little example:

\documentclass{article}
\usepackage{amsthm}
\usepackage[framemethod=tikz]{mdframed}
\usepackage{lipsum}% just to generate text for the example

\newtheorem{theo}{Theorem}
\surroundwithmdframed[outerlinewidth=0.4pt,
innerlinewidth=0.4pt,
middlelinewidth=1pt,
middlelinecolor=white,
bottomline=false,topline=false,rightline=false]{theo}

\begin{document}

\begin{theo}
\lipsum[4]
\end{theo}

\end{document}


A simple variation of the above code produces a double ruled frame:

\documentclass{article}
\usepackage{amsthm}
\usepackage[framemethod=tikz]{mdframed}
\usepackage{lipsum}

\newtheorem{theo}{Theorem}
\surroundwithmdframed[outerlinewidth=0.4pt,
innerlinewidth=0.4pt,
middlelinewidth=1pt,
middlelinecolor=white]{theo}

\begin{document}

\begin{theo}
\lipsum[4]
\end{theo}

\end{document}


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