We use the following Boolean variables:
\begin{itemize}
    \item $a$ represents ``The robot visits region A''
    \item $b$ represents ``The robot visits region B''    
    \item $c$ represents ``The robot visits region C''  
\end{itemize}

\begin{itemize}
    \item $\varphi_1 \coloneqq AG (a \rightarrow Xc \vee XXc)$
    \item $\varphi_2 \coloneqq EG (a \rightarrow Xc \vee XXc)$
\end{itemize}