Assignment Questions 1. Let p, q, r, and s be propositiona variables. Which of the following expressions would not be formulas in conjunctive normal form? Why? (a) (b) (c) p V pV p pAqAr (PA q) V (pA r) (h) -(p V q Vr) 2. (This exercise is a variation of Exercise 4.5 in Chapter 4 of the textbook) Consider the set of formulas (a) Transform S into a set of formulas in CNF, S (b) Transform S' into a set of formulas in clausal form, S" (c) Prove using resolution that S" is unsatisfiable 3. (Exercise 4.4 in Chapter 4 of the textbook) Given the set of clauses (par, pr, qr, r], construct two refutations (i.e. demonstrate using the resolution procedure that the set of clauses is unsatisfiable) (a) one by resolving the literals in the order (p, q, rh (b) and the other in the order fr, q, p]