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:

Given the following two statements:

$$\left( {{S_1}} \right):\left( {q \vee p} \right) \to \left( {p \leftrightarrow \sim q} \right)$$ is a tautology

$$\left( {{S_2}} \right): \,\,\sim q \wedge \left( { \sim p \leftrightarrow q} \right)$$ is a fallacy. Then: