A contrapositive of a conclusion \(x \Rightarrow y\) is a proposition, in which the antecedent \(x\), and the consequent \(y\) are inverted and negated, formally
\[\neg y\Rightarrow\neg x\] is the contrapositive of \[x\Rightarrow y.\]
We read the contrapositive \(\neg y\Rightarrow\neg x\) \["\text{if not }y,\text{ then not }x".\]