Let Seq (x, y) be the set of all strings (of length 1 or more) composed of alternating x's and y's. For example, Seq (a, b) contains a, b, ab, ba, aba, bab, abab, baba, and so on. Write a regular expression that defines Seq(x, y).

Let S be the set of all strings (of length 1 or more) composed of a's, b's, and c's that start with an a and in which no two adjacent characters are equal. For example, S contains a, ab, abc, abca, acab, acac, . . . but not c, aa, abb, abcc, aab, cac, . . . . Write a regular expression that defines S. You may use Seq_x_ y_ within your regular expression if you wish.