The negation of the Boolean expression p $$ \vee $$ (~p $$ \wedge $$ q) is equivalent to :

The statement
$$\left( {p \to \left( {q \to p} \right)} \right) \to \left( {p \to \left( {p \vee q} \right)} \right)$$ is :

The negation of the Boolean expression x $$ \leftrightarrow $$ ~ y is equivalent to :

Contrapositive of the statement :
‘If a function f is differentiable at a, then it is also continuous at a’, is: