\documentclass[12pt]{article}
\usepackage{amsmath,amsfonts,amssymb}
\usepackage{xepersian}
\begin{document}
\renewcommand{\theenumi}{\roman{enumi}}
\begin{enumerate}
\begin{latin}
\item $\vdash S \Longrightarrow\ \vdash$
\item $\vdash T\rightarrow$
\item $\vdash d \rightarrow$
\end{latin}
\item $t+5$ یک \Sigma ـ جمله است.
\end{enumerate}
\end{document}