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\begin{document}
  \begin{equation}
	\sum_{a  \in A} x_{a} \mathcal{R}_{i}(a) 
	\geq 
	\sum_{a  \in A} x_{a} \mathcal{R}(a^{"}_{i}, a_{-i}) \quad \forall i \in , a^{"} \in A_{I}
\end{equation}
\end{document}}