Discrete Structures - Old Questions

16. Construct truth tables to determine whether the given statement is a tautology a contingency or an absurdity.

a) p ⇒ (q ⇒p)

b) q ⇒ (q ⇒p)

c) p ∧ ~ p

OR

Explain the method of proving theorems by direct indirect, controdiction and by cases.