# No space before or after the theorem environment

I am sorry if this have been asked before, but I tried searching for similar questions and none of them answered my issue.

I defined a new theorem environment style, which I called "slanted." However, despite using \topsep, the new theorem style is not separated by any space from above or below. Does anyone know why that could be the case? Is it possible that my preamble is defined incorrectly? Below you can find the preamble that I am using together with the produced output (for comparison, I also included the definition and remark environments). Any help would be greatly appreciated.

EDIT 1: This issue has to have something to do with me using amsart. But why? Why can't I properly define new theorem styles in amsart? I am fairly new to amsart, so maybe that is the case. Do I even need to load amsmath, amssymb and amsthm or are they loaded automatically when I use amsart?

\documentclass[12pt]{amsart}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{times,newtxmath}

\newtheoremstyle{slanted}
{\topsep}%   Space above
{\topsep}%   Space below
{\slshape}%  Body font
{}%          Indent amount (empty = no indent, \parindent = para indent)
{0.5em}%     Space after thm head: " " = normal interword space;
%         \newline = linebreak
{}%          Thm head spec (can be left empty, meaning normal')

\theoremstyle{slanted}
\newtheorem{theorem}{Theorem}

\theoremstyle{definition}
\newtheorem*{de}{Definition}

\theoremstyle{remark}
\newtheorem*{rem}{Remark}

\begin{document}

Mathematicians resolve the truth or falsity of conjectures by mathematical proof.
\begin{theorem}
Mathematicians seek out patterns.
\end{theorem}

Mathematicians resolve the truth or falsity of conjectures by mathematical proof.
\begin{de}
Mathematicians seek out patterns.
\end{de}

Mathematicians resolve the truth or falsity of conjectures by mathematical proof.
\begin{rem}
Mathematicians seek out patterns.
\end{rem}

Mathematicians resolve the truth or falsity of conjectures by mathematical proof.
\end{document}


• amsthm is built into amsart (and all other ams document classes). the skip above is called something like \pre@thm@skip (i probably have the @ signs in the wrong place, but i don't have a working tex system on my laptop to check). you can search for the value in amsart.cls. it's lots bigger than what you've used, and the value used in amsart may be slightly different than the value used in the standalone amsthm (don't remember). (amsmath and amsfonts are automatically loaded but that is irrelevant here; amssymb is not loaded.) – barbara beeton Mar 25 '17 at 3:02

You have a \topsep of roughly 2.5pt plus 2.5pt, that is hardly noticed. With some like \setlength{\topsep}{5em} before of the new theorem style definition, you will see a big space before and after the theorem.

But instead of change a length that could be used elsewhere, it could be better use a new length for this, or just some like:

\newtheoremstyle{slanted}
{1em plus .2em minus .1em}%   Space above
{1em plus .2em minus .1em}%   Space below
....

• Thank you @Fran! That works. Do you know by any chance what the default space before and after the definition environment is? I would like to set my theorem environment to have the same spacing. – Pawel Mar 24 '17 at 20:59
• @Pawel Put \the\topsep after \begin{document} and remove \setlength{\topsep}{5em} and you will see default value of \topsep`. – Fran Mar 24 '17 at 21:11
• Thank you Fran. I am sorry for asking so many questions, but if the topsep is set to be 2.5, does the definition environment also use that spacing? In other words, if the definition environment uses topsep, then why did my definition and theorem environments look different? – Pawel Mar 24 '17 at 21:15
• @Pawel No, as far I see in your MWE. – Fran Mar 24 '17 at 21:23