通过逆否命题来证明

1. What’s Contrapositive?

The contrapositive of a conditional statement is a logically equivalent statement that is formed by negating both the hypothesis (the “if” part) and the conclusion (the “then” part) of the original statement and then reversing their order.

For a given conditional statement in the form of “If P, then Q” (symbolically represented as P → Q), the contrapositive is “If not Q, then not P” (symbolically represented as ¬Q → ¬P).

2. Why Is Contrapositive Important?

1. Logical Equivalence: The contrapositive of a statement is always logically equivalent to the original statement. This means that if the origi