This is a follow-up question of this question.
when using \begin{theorem}[Open mapping]...\end{theorem},
I received
Is it possible to change the format into "Theorem: Open Mapping."(boldface)?
Thanks a lot!
[Tex/LaTex] How to remove brackets from the optional title in amsthm
amsthmformattingtheorems
Related Solutions
The style "plain" should be equivalent to
\newtheoremstyle{plain}
{\topsep} % ABOVESPACE
{\topsep} % BELOWSPACE
{\itshape} % BODYFONT
{0pt} % INDENT (empty value is the same as 0pt)
{\bfseries} % HEADFONT
{.} % HEADPUNCT
{5pt plus 1pt minus 1pt} % HEADSPACE
{} % CUSTOM-HEAD-SPEC
The style "definition" is the same except for the body font, which is \normalfont; in "remark" the spaces above and below are 0.5\topsep, the head font is \itshape and the body font is \normalfont.
You could define your own shortthm environment:
\documentclass{article}
\usepackage{lipsum}% http://ctan.org/pkg/lipsum
\usepackage{amsthm}% http://ctan.org/pkg/amsthm
\newtheorem{thm}{Theorem}
\makeatletter
\newenvironment{shortthm}
{\enskip\refstepcounter{thm}\textbf{Theorem~\thethm.\space}\itshape}% \begin{shortthm}
{\enskip}% \end{shortthm}
\makeatother
\begin{document}
\lipsum[1]
\begin{thm}
This is a theorem
\end{thm}
\lipsum[2]
Example text before theorem. \begin{shortthm}This is a theorem.\end{shortthm} Example text after theorem.
\end{document}
Note that this usage might be confusing to readings, since there is no clear distinction between the theorem body and body text - provided by default when using the line break of amsthm.
The above shortthm is very crude, but could be extended to form part of the creation when issuing \newtheorem{<theorem>}{<title>}. Also, it could also be made a macro, but I kept it in an environment form. The preceding and following text is separated by \enskip; assuming of course that you're not starting a paragraph with it. However, that can also be modified.
Best Answer
the optional element of a theorem heading is designated as
\thmnote, but this isn't defined inamsthmas an independent element. it is expanded in two places, one for theorem headings with the number following the main heading word, and (as you have it) with the numbers "swapped" as for section headings using\swapnumbers.probably the easiest way to produce the style you want -- all bold, a colon after the heading word, and no parentheses -- is to redefine the internal command for the swapped form of the heading:
i've left the original definition with
\thmnotecommented out so that you can see how the change in spacing is applied. the\thm@notefontand the extra braces to isolate its invocation are omitted since the default font isn't changed.changes of this sort are requested from time to time, so i will take this as a formal request to consider allowing variations in the style of the optional element to be made more easily, when the package is overhauled (perhaps late next year).