乳胶中的证明结构

Question

针对文本显示为斜体的问题，我制定了自己的定义来证明。这是因为\begin{lexproof}在 中调用了\begin{theorem}。

\newenvironment{lexproof}
   {
     \paragraph{Proof:}
   }
   {\hfill \textdagger}


\newpage
\section{Pythagoreas} 

\begin{theorem}[Pythagorean theorem]
   A theorem about right triangles summarised by the equation
   \[ x^2 + y^2 = z^2 \]

   \begin{lexproof}
      To prove it by contradiction try and assume that the statement i s
      false, proceed from there and at some point you will arrive to a
      contradiction.
   \end{lexproof}

\end{theorem}