(a) The two-digit Boolean function XOR (O) is defined by: a ob= { if a + b else 0 Give the truth tables and the index sets for the Boolean functions NOT (1), AND (-), OR (+) and XOR (O). (b) Let I (f) = {0, 2, 11, 15, 17, 21, 23, 31} be the index set of a Boolean function feF(5). What is the disjunctive normal form of the Boolean term e ET(5) that describes f? Note: Some sources differentiate between normal forms and canonical or complete normal forms. When we speak of disjunctive or conjunctive normal form, we always mean the complete normal form, matching the definition from the lecture