\begin{enumerate}
\item \textbf{Decide entailment using satisfiability.}
The question whether $\varphi \vDash  \psi$ can be decided by checking $\varphi \wedge \neg \psi$ not satisfiable.

\item \textbf{Decide entailment using validity.}
The question whether $\varphi \vDash \psi$ can be decided by checking $\varphi \rightarrow \psi$ is valid.
\end{enumerate}
