begin{Proof}...\end{Proof} 命令出错

Question

我写了以下代码：

\documentclass[12pt]{article}  
\usepackage{amsmath}  
\usepackage{amssymb}   
\usepackage{amsthm}  
\newtheorem{theorem}{Theorem}  
\newtheorem{lemma}{Lemma}  

\begin{document}  

\begin{lemma}   
My lemma  
\end{lemma}   

\begin{Proof}  
My proof  
\end{Proof}  

\end{document}  

显示以下错误

! LaTeX Error: Environment Proof undefined.  
See the LaTeX manual or LaTeX Companion for explanation.  
Type H <return> for immediate help.  
...  
l.15 \begin{Proof}  
Your command was ignored.  
Type I <command> <return> to replace it with another command,  
or <return> to continue without it.  
! LaTeX Error: \begin{document} ended by \end{Proof}.  
See the LaTeX manual or LaTeX Companion for explanation.  
Type H <return> for immediate help.  
...  
l.17 \end{Proof}  
Your command was ignored.  
Type I <command> <return> to replace it with another command,  
or <return> to continue without it.

请帮忙。

Answer 1

问题在于区分大小写：Proof应该是proof。请尝试使用

\begin{proof}
My Proof
\end{proof}