\hline 产生“未定义的控制序列”

Question

我不知道为什么像这样的正确代码会在每个 \hline 处产生“未定义的控制序列”：

\begin{center}
\begin{tabular}{ |c|c|c| } 
 \hline
 cell1 & cell2 & cell3 \\ 
 cell4 & cell5 & cell6 \\ 
 cell7 & cell8 & cell9 \\ 
 \hline
\end{tabular}
\end{center}

也许这和我的进口有关？

\usepackage[preprint]{neurips_2019}
\usepackage{arydshln}

\usepackage[utf8]{inputenc} % allow utf-8 input
\usepackage[T1]{fontenc}    % use 8-bit T1 fonts
\usepackage{url}            % simple URL typesetting
\usepackage{booktabs}       % professional-quality tables
\usepackage{amsfonts}       % blackboard math symbols
\usepackage{nicefrac}       % compact symbols for 1/2, etc.
\usepackage{microtype}      % microtypography

\usepackage{graphicx}
\usepackage{subfigure}
\usepackage{multirow}
\usepackage{natbib}
\usepackage{threeparttable}
\usepackage{makecell}
\usepackage{booktabs} % for professional tables
\usepackage{float} %to fix figures



\usepackage{amsfonts,amsmath,amssymb,amsthm,mathtools} % various math stuff
\usepackage{wrapfig}  % Allow wrapping of text around figures
\usepackage{mdwlist}  % Make list items closer together: itemize*, enumerate*
\usepackage{sidecap}  % For putting caption beside figure
\usepackage{bbm}
\usepackage{bm,amsbsy} % for bold symbols

% \usepackage{subcaption}  % apparently contains errors
\usepackage{caption}
\usepackage{xcolor}
\usepackage{algorithm,algorithmic}

\usepackage{hyperref}       % hyperlinks

Answer 1

注释掉：

\usepackage{arydshln}

解决了这个问题。