我使用 LyX 进行数学输入已经有一段时间了。到目前为止，我一直在使用“标准冠词”类，一切运行良好。但是当我尝试使用 AMS 冠词类时，我收到此错误（即使文档为空）：
! Undefined control sequence.
\moreL ...dL \beginL \csname from\@rllanguagename
\endcsname
l.18 \begin{document}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.
! Undefined control sequence.
\moreL ...dL \beginL \csname from\@rllanguagename
\endcsname
l.18 \begin{document}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.
LaTeX Font Info: Font shape `HE8/cmr/m/n' will be
(Font) scaled to size 10.0pt on input line 18.
(newfile1.aux) )
前面几行还提到了这一点：
Package babel Warning: No hyphenation patterns were preloaded for
(babel) the language `Hebrew' into the format.
(babel) Please, configure your TeX system to add them and
(babel) rebuild the format. Now I will use the patterns
(babel) preloaded for english instead on input line 57.
这是产生问题的代码（它也发生在空文档中）：
\documentclass[oneside,english,hebrew]{amsart}
\usepackage[T1]{fontenc}
\usepackage[latin9,cp1255]{inputenc}
\usepackage{amsthm}
\makeatletter
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Textclass specific LaTeX commands.
\numberwithin{equation}{section}
\numberwithin{figure}{section}
\makeatother
\usepackage{babel}
\begin{document}
\selectlanguage{english}%
\inputencoding{latin9}hello\selectlanguage{hebrew}%
\end{document}
我在 Windows 机器上使用 pdf(la)tex 和 LyX 2.1.3，安装了 MiKTeX 2.9。谢谢。
答案1
@Ulrike Fischer 指出
amsart在 中进行一些排版，AtBeginDocument-hook但并非所有 babel 命令都已设置。因此，当它遇到@brackets中的命令时会中断\leftmarginii。尝试\makeatletter \def\@rllanguagename{hebrew} \makeatother