= Given alphabet A = {a,b,c} answer the following questions. a) Let L be the set of words over A, in which the letters are in alphabetical order, for example abc, aabbbc, ac, bbbc. Write down a regular expression for L. b) Which of the following regular expressions are equivalent to each other? Justify your answer. 1. cab(ab)* 2. c(aba)*b 3. ca(ba)*b