在普通的定理样式中覆盖斜体列表计数器

Question

在任何用 \theoremstyle{plain} 定义的定理中使用列表环境都会产生斜体计数器。即以下示例

\usepackage{amsthm}
\usepackage{enumerate}

\theoremstyle{plain}
\newtheorem{theorem}{Theorem}

\begin{theorem}
The following are not equivalent.
\begin{enumerate}
\item $n$ is an even integer.
\item $n$ is divisible by 4.
\item $n$ is 3 more than some positive odd integer.  
\end{enumerate}
\end{theorem}

生成斜体计数器 (1)、(2) 和 (3)。如何覆盖此操作？

Answer 1

您可以明确指定标签格式：

\begin{enumerate}[{\normalfont 1.}] % (or \upshape)
\item $n$ is an even integer.
\item $n$ is divisible by 4.
\item $n$ is 3 more than some positive odd integer.  
\end{enumerate}

或者，如果您不坚持使用该enumerate包，并且您将经常需要它，那么您可以使用该enumitem包，并设置一次标签：

\documentclass{article}
\usepackage{amsthm}
\usepackage{enumitem}

\theoremstyle{plain}
\newtheorem{theorem}{Theorem}
\setenumerate{label={\normalfont\arabic*.}} % or \upshape
\begin{document}
\begin{theorem}
The following are not equivalent.
\begin{enumerate}
\item $n$ is an even integer.
\item $n$ is divisible by 4.
\item $n$ is 3 more than some positive odd integer.  
\end{enumerate}
\end{theorem}

\end{document}