我可能误解了文档，但我相信如果我amsmath在声明中使用该包，那么输入\qed应该会给我一个 QED 符号。当我这样做时，它会崩溃undefined control sequence。
片段：
\documentclass[11 pt]{article}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{graphicx}
\graphicspath{{/texfiles/}}
\begin{document}
...
Since we proved that any function with the property ($\pi$) is an increasing involution, we have thus proved that $f(x) = x$ is the only function which satisfies ($\pi$).
\qed
这里出了什么问题？
答案1
您需要amsthm以下软件包：
\documentclass[11 pt]{article}
\usepackage{amsmath,amsthm}
\usepackage{amsfonts}
\usepackage{graphicx}
\graphicspath{{/texfiles/}}
\begin{document}
...
Since we proved that any function with the property ($\pi$) is an increasing involution,
we have thus proved that $f(x) = x$ is the only function which satisfies ($\pi$).
\qed
\end{document}