\documentclass[12pt , a4paper]{report}
\usepackage[all]{xy}
\usepackage{amsthm, amssymb, amsmath,amsfonts,fancyhdr,color,xspace,hyperref,latexsym,amscd,tikz}
%\usepackage{amsthm, amssymb, amsmath,amsfonts,fancyhdr,color,xspace,hyperref,latexsym,amscd,tikz} 
%\usepackage{glossaries}
\usepackage[twoside,top=26mm, bottom=21mm, left=20mm, right=20mm]{geometry}
%\fancyhead{} 
%\fancyhead[L]{\slshape \rightmark}
%\fancyhead[R]{\slshape \leftmark}
\usepackage{graphicx}
\usepackage[pagebackref=false,colorlinks,linkcolor=blue,citecolor=magenta]{hyperref}
\pagestyle{fancy}
\usepackage{graphicx}
\fancyfoot{} 
\fancyfoot[C]{\thepage}
\renewcommand{\headrulewidth}{0.6pt}
\usepackage{xepersian}
\settextfont[Scale=1.2]{Yas}
\setlatintextfont[ExternalLocation,BoldFont={lmroman10-bold},BoldItalicFont={lmroman10-bolditalic},ItalicFont={lmroman10-italic}]{lmroman10-regular}
\setdigitfont[Scale=1.2]{Yas}
\linespread{2}
\defpersianfont\nastaliq[Scale=1]{IranNastaliq}
\linespread{2}
\usepackage[nottoc]{tocbibind}
\include{references}



\theoremstyle{definition}\newtheorem{de}{تعریف}[section]
\theoremstyle{plain}\newtheorem{thh}[de]{قضیه}
\theoremstyle{plain}\newtheorem{pr}[de]{گزاره}
\theoremstyle{plain}\newtheorem{rem}[de]{نکته}
\theoremstyle{plain}\newtheorem{lee}[de]{لم}
\theoremstyle{plain}\newtheorem{cor}[de]{نتیجه}
\theoremstyle{plain}\newtheorem{coro}[de]{فرع}
\theoremstyle{definition}\newtheorem{exa}[de]{مثال}
\theoremstyle{plain}\newtheorem{rema}[de]{تذکر}
\theoremstyle{plain}\newtheorem{qu}[de]{سؤال}
%renewcommand\proofname{\textbf{برهان}}
\renewcommand{\bibname}{\textbf{مراجع}}

\newcommand\persiangloss[2]{#1\dotfill\lr{#2}\\}
% دستوری برای تعریف واژه‌نامه فارسی به انگلیسی 
\newcommand\englishgloss[2]{#2\dotfill\lr{#1}\\}

\pagenumbering{arabic}
%\makeglossaries
\begin{document}
\begin{align*}
F_ \alpha \circ( F_\beta\circ F_\gamma)(x, \theta)_{\rho^*}&=\bigcup \{p: p \in F_{\alpha} (r)\;\; where\;\;\; r \in F_{\beta} \circ F_{\gamma} (x, \theta)_{\rho^*}\}
\end{align*}
\end{document}