%% LyX 1.3 created this file.  For more info, see http://www.lyx.org/.
%% Do not edit unless you really know what you are doing.
\documentclass[oneside,english,hebrew]{amsart}
\usepackage[latin1,cp1255]{inputenc}
\usepackage{amssymb}

\makeatletter
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Textclass specific LaTeX commands.
 \theoremstyle{plain}    
 \newtheorem{thm}{Theorem}[section]
 \numberwithin{equation}{section} %% Comment out for sequentially-numbered
 \numberwithin{figure}{section} %% Comment out for sequentially-numbered
 \theoremstyle{plain}

\usepackage{babel}
\makeatother
\begin{document}
\selectlanguage{english}
\inputencoding{latin1}
regular text works fine

\selectlanguage{hebrew}
\inputencoding{cp1255}
עברית - גם בסדר

\selectlanguage{english}
\inputencoding{latin1}

\section*{Part{*}, Section{*}, ..., Subparagraph{*} forks fine!}


\section{Part, Section, ..., subsubsection (all are numbered) cause troubles
even in English}

\begin{thm}
Theorem, Corollary,Lemm and lots of others. (both numbered and not)
don't work
\end{thm}
\begin{itemize}
\item Proof, Quotation, Quote, Itemize, Enumerate, Description and List
work well
\selectlanguage{hebrew}
\end{itemize}

\end{document}