Contrapositive

The

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

that is

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

(Levin, 2021, sec. 0.2)

• Example