Questionnaire-2024/natural_deduction_predicate_logic/multiple_choice/4_1_fol_lect_sol.tex

\item \lect Considering \textit{Quantifier Equivalences} in \textit{Natural Deduction} for \textit{Predicate Logic}, tick all statements in the list, that are equivalent.

\begin{itemize}
    \item[$\square$] $\forall x \; \phi \equiv \exists x \; \lnot \phi$
    \item[$\ticked$] $\forall x \; \phi \equiv \lnot \exists x \; \lnot \phi$
    \item[$\ticked$] $\lnot \forall x \; \phi \equiv \exists x \; \lnot \phi$
    \item[$\square$] $\exists x \; \lnot \phi \equiv \lnot \forall x \; \lnot \phi$
\end{itemize}