# Bold small-caps header of theorems in amsbook

I'm using amsbook with amsthm. It seems that amsbook customized the theorem environment so that the theorem name (eg Theorem 1) is written in big caps and small caps, which is fine for me. But I want to make it bold. How to do it?

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In order to get bold small-caps in the header of a theorem, you'll need to "patch" two commands inside the \@thm macro, as is done in the following MWE:

\documentclass{amsbook}
\usepackage[T1]{fontenc}
%\usepackage{newtxtext,newtxmath} % optional, e.g., if you want Times Roman font family
\usepackage{etoolbox}
\makeatletter
\patchcmd{\@thm}{\thm@notefont{\fontseries\mddefault\upshape}}{}{}{}
\makeatother
\newtheorem{theorem}{Theorem}
\begin{document}

\begin{theorem}[Pythagoras]
Let the lengths of the sides of a right triangle be denoted by $a$, $b$,
and $c$, and assume w.l.o.g.\ that $a\le b<c$. Then $a^2+b^2=c^2$.
\end{theorem}
\end{document}


Addendum: Just for comparison, here's the look that would result without the patches:

I don't want to pass judgment on which style looks better. However, it's worth pointing out that, from an overall design point of view, it is often questionable to use two methods of visual emphasis simultaneously (in the first case above, the joint use of small-caps and of bold). I suppose this design issue may be one of the reasons why the original Computer Modern fonts didn't include bold-smallcaps, italic-smallcaps, etc combinations.

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+1, but I'd also note that "double emphasis" is something to avoid whenever possible. – egreg Jul 15 '12 at 15:08
@egreg -- Thanks for pointing out this issue -- I fully agree with it. – Mico Jul 15 '12 at 15:10
thanks, it works. – steven Jul 15 '12 at 16:09