4. (5 marks) Consider the following schedule, where r(v) means that transaction i reads object v and wi(v) means that transaction i writes to object v. r2(x) r3(y) f(x) wa(y) w(x) ra(y) r(z) wa(y) rz(y) ra(z) w(y) (a) (2 mark) List all pairs of conflicting operations in this schedule. (b) (2 mark) Draw the conflict graph for this schedule. (c) (1 mark) If the schedule is serializable, give an equivalent serial schedule. If it is not serializable, then explain why not.