Equivalence of a statement without using the equivalence symbol

Question

Is it possible to express $a \Leftrightarrow b$ using only ($\neg$) and ($\Rightarrow$)?

For example $ a \wedge b$ can be expressed as $\neg(a \Rightarrow \neg b)$. Both statements produce the same truth table.

Answer 1

Hint

$A \Leftrightarrow B$ is $(A \Rightarrow B) \land (B \Rightarrow A)$ and you know how to express $\land$.