\documentclass[oneside,openany,msc]{Bojnord_thesis}
\begin{document}
\baselineskip=.75cm
\pagenumbering{harfi}
\pagenumbering{arabic}
\baselineskip=.75cm

\begin{align*} 
{\left[ x \right]_\theta } \subseteq A,{\left[ y \right]_\theta } \subseteq A&\ \ \Rightarrow\ \{\left[ x \right]_\theta }.{\left[ y \right]_\theta } \subseteq A \cdot A \subseteq A\\ 
&\ \ \Rightarrow\ \{\left[ {x \cdot y} \right]_\theta } \subseteq A\\ 
&\ \ \Rightarrow\ \{\left[ x \right]_\theta } \odot {\left[ y \right]_\theta } \subseteq A\\
&\ \ \Rightarrow\ \{\left[ x \right]_\theta } \odot {\left[ y \right]_\theta } \in {{\underline \theta (A)} \mathord{\left/
{\vphantom {{\underline \theta (A)} \theta }} \right.
\kern-\nulldelimiterspace} \theta }\\
\end{align*} 


\begin{align*} 
(a,a) \in L \cap R,a \in A&\ \ \Rightarrow\ \ a \in \mathop {\left[ a \right]}\nolimits_{L \cap R} \cap A\\ 
&\ \ \Rightarrow\ \ \mathop {\left[ a \right]}\nolimits_{L \cap R} \cap A \ne \emptyset \\
&\ \ \Rightarrow\ \ a \in \overline {L \cap R} (A) \\ 
\end{align*}
 
\end{document}