Problem 5: (express the language in terms of basic set operations) a) Prove that if L1 and L2 are regular then L\L2 (set difference) is also regular. b) The symmetric difference of two sets S1 and S2 is defined as: SOS = {x:xe S or xe S but x is not in both S1 and S2}. Show that the family of regular languages is closed under symmetric difference.