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Consider the sentence $\phi = \exists x \forall y (P(x,y) \implies (Q(x,y) \lor R(x,y)))$.
Does the following model satisfy $\phi$?
The model $M$ consists of:
\begin{itemize}
\item $A = \{a, b, c\} $
\item $P^{M} = \{(a,a), (a,b), (b,a), (b,b), (c,a), (c,b)\}$
\item $Q^{M} = \{(a,m) | m \in A \}$
\item $R^{M} = \{(a,a), (b,a), (a,c), (b,c), (c,c)\}$
\end{itemize}
% \item The model $M'$ consists of:
%\begin{itemize}
%\item $A = \mathbb{Z} $
%\item $P^{M} = \{(m,n) | m \ge n \}$
%\item $Q^{M} = \{(m,n) | m \le n \}$
%\item $R^{M} = \{(m,n) | m = -n \}$
%\end{itemize}