\documentclass{book}
\usepackage{graphicx}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsthm}

\usepackage{xepersian}
\begin{document}
\begin{itemize}
\begin{LTRitems}
\item 
x=_{P, G} y\Longleftrightarrow x=_{P, 1} y\ \& ... \&\  x=_{P, m} y,
\item 
x\leqslant_{P, G}y\Longleftrightarrow x\leqslant_{P, 1} y\ \& ... \&\ x\leqslant_{P, m} y,
\end{LTRitems}
\end{itemize}
\end{document}