deletions | additions       diff --git a/section_Definitions_Theorems_Lemmas_and__.tex b/section_Definitions_Theorems_Lemmas_and__.tex  index c9e0342..f7008fb 100644  --- a/section_Definitions_Theorems_Lemmas_and__.tex  +++ b/section_Definitions_Theorems_Lemmas_and__.tex 
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\href{https://en.wikipedia.org/wiki/AMS-LaTeX}{AMS-flavored} \LaTeX introduces a flexible language for declaring custom types of environments. It has long been the weapon of choice for declaring mathematical statements, for example:  \begin{lstlisting}  % Declare in header.tex:  \newtheorem{theorem}{Theorem}  \newtheorem{proof}{Proof}  % ...  % And later use:  \begin{theorem}[Pythagoras] Suppose $a\leq b\leq c$ are the side-lengths of a right triangle.\\ Then $a^2+b^2=c^2$.\end{theorem}  \begin{proof}. . . \end{proof}  \end{lstlisting}