I understand how to use the theorem environment in LaTex and would like to know if there is a similar environment for postulates or how I can make an environment for postulates on my own.
[Tex/LaTex] Creating a Postulate Environment
environmentstheorems
Related Solutions
Since you would like to use the standard LaTeX theorem commands, here's a solution for that: let's insert \newline\quote into the beginning of a theorem and \endquote at the end. A complete compilable example for this:
\documentclass{article}
\makeatletter
\def\@begintheorem#1#2{\trivlist
\item[\hskip \labelsep{\bfseries #1\ #2}]\mbox\newline\quote\itshape}
\def\@opargbegintheorem#1#2#3{\trivlist
\item[\hskip \labelsep{\bfseries #1\ #2\ (#3)}]\mbox\newline\quote\itshape}
\def\@endtheorem{\endquote\endtrivlist}
\makeatother
\newtheorem{thm}{Theorem}
\begin{document}
\section*{The Theorem of Pythagoras}
Text body. Text body. Text body.
\begin{thm}[Pythagoras]
Let $a,b,c$ the sides of a rectangular triangle.
Without loss of generality, we assume that $a<b<c$ .
Then, the following equality holds:
\[a^2 + b^2 = c^2\]
\end{thm}
More text. And even more text.
\end{document}
Output:
That's a point to start for you. You may insert additional commands of your own regarding spacing and formatting. For instance you may notice that I used \mbox before \newline to get a line break - if I write \mbox{} instead there would be more space, if I omit it there cannot be a line break at this point (or use \leavevmode). Simply writing \par instead of \newline would not work.
You may also consider to use one of these useful theorem packages:
Both offer commands for customizing theorem layouts.
You can use the amsthms customisable theoremstyles to do this. The trick is just figuring out what arguments to pass! By trial-and-error, I came up with the following:
\documentclass{minimal}
\usepackage{amsthm}
\newtheorem*{theorem}{Theorem}
\newtheoremstyle{named}{}{}{\itshape}{}{\bfseries}{.}{.5em}{\thmnote{#3's }#1}
\theoremstyle{named}
\newtheorem*{namedtheorem}{Theorem}
\begin{document}
Now let us present that most famous of all theorems.
\begin{theorem}[Fred]
All odd numbers are prime.
\end{theorem}
If you don't believe that Fred was involved, you may prefer the following.
\begin{theorem}
All odd numbers are prime.
\end{theorem}
The proof of this is left as an exercise.
Of course, some may prefer to see this as follows.
\begin{namedtheorem}[Fred]
All odd numbers are prime.
\end{namedtheorem}
But still, we shan't bother with the proof here.
As we said, some people don't think that Fred had much to do with this.
\begin{namedtheorem}
All odd numbers are prime.
\end{namedtheorem}
Nonetheless, the proof remains trivial.
\end{document}
Here's the result. Note that the first theorem is in the default style so it's the second pair that you should be looking at.
(Added in edit: I wasn't clear what \thmnote was doing; a little further experimenting shows that if the optional argument isn't given then \thmnote swallows its argument whole so it can be used to change the behaviour depending on whether or not the argument is given. This makes it look better if you do forget the Fred.)
Best Answer
or
in the preamble should be enough. Now you can use packages, such as
amsthmorntheoremto customise the layout of this new environment.