# Theorems and Definitions as quotes

Most standard styles highlight theorems and definitions using italics. Now this is something I really would like to avoid in my thesis (and generally). Unfortunately, if I just remove this "feature", I am left with the problem that it isn't obvious anymore where a theorem ends and the normal body text continues. I am wondering whether there is a not-too-complicated way to make theorem environments visually like quote environments, i. e. greater horizontal offset. What should I do?

An additional question in case this is too easy: What if I don't just want a greater horizontal offset, but also a vertical line on the level of the normal offset going all the way down until the end of the theorem?

## 1 Answer

For the first question, you can define a new environment using the quote environment and some therem-like structure from, for example, the amsthm package; for the second question, the leftbar environment from the framed package can be useful. A little example that you can use as starting point:

\documentclass{article}
\usepackage{amsthm}
\usepackage{framed}
\usepackage{lipsum}

\theoremstyle{definition}
\newtheorem{theo}{Theorem}
\newenvironment{Qtheorem}[1][]
{\quote\begin{theo}[#1]}
{\end{theo}\endquote}
\newenvironment{Btheorem}[1][]
{\begin{theo}[#1]\begin{leftbar}}
{\end{leftbar}\end{theo}}

\begin{document}

\lipsum[1]
\begin{Qtheorem}
\lipsum[1]
\end{Qtheorem}
\lipsum[1]
\begin{Btheorem}
\lipsum[1]
\end{Btheorem}

\end{document}

• or switch to the ntheorem package, which can do even wilder markings – daleif Mar 28 '11 at 21:08
• Hi Gonzalo, thanks a lot, but I'm getting errors like these: pastebin.com/PKXP8ekw Could you comment on what I'm doing wrong? – darij grinberg Mar 28 '11 at 22:08
• @darij grinberg: you are using \newtheorem{lemma}[theorem]{Lemma} but I defined theo instead of theorem, so simply change \newtheorem{lemma}[theorem]{Lemma} to \newtheorem{lemma}[theo]{Lemma} – Gonzalo Medina Mar 28 '11 at 22:18
• This doesn't change anything, I fear. – darij grinberg Mar 28 '11 at 22:19
• @darij grinberg: then, please post a minimal and complete version of your code, so that I can see where the problem is. – Gonzalo Medina Mar 28 '11 at 22:21