Contrapositive
= Contrapositive
{wiki}
The contrapositive of $A\to B$ is $\neg B\to\neg A$. In <classical propositional logic> an implication and its contrapositive are logically equivalent, so either can be proved in place of the other.
= Contrapositive
{wiki}
The contrapositive of $A\to B$ is $\neg B\to\neg A$. In <classical propositional logic> an implication and its contrapositive are logically equivalent, so either can be proved in place of the other.