# Theorem formatting: strange interaction with itemize

This question is related to this one.

I want to have theorem headers alone on a line like this:

Theorem 1.
some text...


In the amsthm documentation, they suggest doing this:

\newtheoremstyle{mystyle}{3pt}{3pt}{}{0pt}{\bfseries}{.}{\newline}{}
\theoremstyle{mystyle}


And it works... as long as the text of the theorem doesn't start with an itemize or an enumeration.

How can I make it work with amsthm in this case?

And... why does this work this (strange) way?

Here is a minimal example to show the problem:

\documentclass{article}
\usepackage{amsthm}

\newtheoremstyle{mystyle} % Name
{3pt}                   % Space above
{3pt}                   % Space below
{}                      % Body font
{0pt}                   % Indent amount
{\bfseries}             % Theorem head font
{.}                     % Punctuation after theorem head
{\newline}              % Space after theorem head
{}                      % Theorem head spec (can be left empty, meaning 'normal')

\theoremstyle{mystyle}
\newtheorem{Example}{Example}

\begin{document}

\begin{Example}
This is on the next line.
\end{Example}

\begin{Example}
\begin{itemize}
\item But this isn't!
\item \ldots
\end{itemize}
\end{Example}

\begin{Example}~
\begin{itemize}
\item And now, there is too much vertical space above
\item \ldots
\end{itemize}
\end{Example}

\end{document}

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see the solution given here tex.stackexchange.com/questions/46357/… –  David Carlisle Mar 23 '12 at 21:18

## 2 Answers

Theorem assumes you start the body with a sentence, not with a list. The following workaround is available: you may start a bogus paragraph and then backtrack a line up:

\begin{Example}\leavevmode\vspace{-\baselineskip}
\begin{itemize}
\item This works
\item \ldots
\end{itemize}
\end{Example}

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do you know how to remove the horizontal space inserted before the 1st item in a default theorem environment? –  Sigur Apr 7 at 12:02

The answer by Boris didn't actually solve my problem, when I had the same. The spacing between the Example X text and the list number wasn't right.

But I realized that I could simply write something like this:

\begin{Example} 
\begin{itemize}
\item This works
\item \ldots
\end{itemize}
\end{Example}


Remark the empty math environment which forces LaTeX the think that there is a text block right after the Example X text.

I just wanted to share my solution, since I wasn't satisfied with the answer provided - I hope it helps somebody.

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