# What's the shortcut?

**Logic**Level 2

\[ (A \iff B)\iff \neg (A \Rightarrow B)\Rightarrow \neg(B\Rightarrow A) \]

There are two ways to prove if a statement is a tautology:

1. Build a truth table

2. Supposing the statmement is false and concluding a contradiction.

Is the mathematical statement at the top a tautology?