1.
Among the two statements

(S1):(pq)(p¬q)(S_1): (p \wedge q) \wedge (p \wedge \neg q) is a contradiction, and

(S2):(pq)(¬pq)(p¬q)(¬p¬q)(S_2): (p \wedge q) \vee (\neg p \wedge q) \vee (p \wedge \neg q) \vee (\neg p \wedge \neg q) is a tautology: