a) Suppose that the statement p-q is false. Find all combinations of truth values of r and s for which (4 - r)A (-p V s) is true. [8 marks] [8 marks] c) Given the relation R = {(1,2), (2,3)} on the set A = {1, 2,3}. What is the minimum number of ordered pairs which when added to R make it an equivalence relation? b) Is (p q) [(p q) - q] a tautology? Why or why not? Discuss your reasoning. [9 marks]