The

reversal and negation

of the constituents of the conditional

\begin{equation*} P \implies Q \end{equation*}

in the form

\begin{equation*} \lnot Q \implies \lnot P, \end{equation*}

which, unlike the converse and inverse, is

equivalent to the original statement,

that is

\begin{equation*} (P \implies Q) \equiv (\lnot Q \implies \lnot P) \end{equation*}

(Levin 2021, sec. 0.2)

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• Example