# Amsbook: Theoremstyles definition and remark identical?

If I understand the documentation of the AMS classes correctly, then a theorem in the style "plain" should have bold heading and italic body text, in the style "definition", there should be bold heading and normal body text, and in "remark", there should be an italic heading and normal body text. This is described her in section 4: http://www-math.mit.edu/~psh/amshelp/2.2/amshelp.pdf

Here, with amsbook, all headings look the same (in small caps), and there is no distinction between "definition" and remark in the body text.

Example:

\documentclass{amsbook}
\theoremstyle{plain}
\newtheorem{thm}{Theorem}
\theoremstyle{definition}
\newtheorem{dfn}{Definition}
\theoremstyle{remark}
\newtheorem{rmk}{Remark}
\begin{document}
\begin{thm}
Here comes a theorem.
\end{thm}
\begin{dfn}
Here comes a definition.
\end{dfn}
\begin{rmk}
Here comes a remark.
\end{rmk}
\end{document}


Is this behaviour correct or is there a problem in my LaTeX environment? I did not find any remarks in the documentation about a different behaviour for amsbook (then for, say, amsart). I also remember that, using an older version of TeXLive, the look of the headings was dependent on whether hyperref was loaded or not.

• The amsbook class changes the theorem styles to suit the general setup of the class. In particular, all theorem headings are in "caps and small caps". Mar 27, 2012 at 16:10
• There is a difference between amsbook.cls (class) theorem styles and amsthm.sty (package) theorem styles. The ones you describe are the ones of amsthm and not of amsbook.
– yo'
Mar 27, 2012 at 16:15

As tohecz mentions in his comment, the difference in the styles that you mention is the one of the amsthm package: however, the amsbook class internally defines the remark and definition styles in a different way. Here are the definitions:

\def\th@definition{%
\let\thm@indent\indent
\thm@preskip.5\baselineskip\@plus.2\baselineskip
\@minus.2\baselineskip
\thm@postskip\thm@preskip
\upshape
}
\def\th@remark{%
\let\thm@indent\indent

As you can see, both styles behave exactly the same when using amsbook.cls.
• Thanks, that difference was not clear to me. Meanwhile, I also looked at amsclass.dtx and at least understood some parts. Mar 28, 2012 at 9:59