1.
Among the statements

(S1):(p∨q)∨((¬p)∧q)(S1): (p \lor q) \lor ((\neg p) \land q) is a tautology

(S2):(q⇒p)⇔((p)∧q)(S2): (q \Rightarrow p) \Leftrightarrow ((p) \land q) is a contradiction

which of the following is correct?