Answers to Problem 6.1 on page 191.

(a) All palindromes of even length over {a,b}.

(b) All palindromes over {a,b}.

(c) All strings over {a,b} that fail to be a palindrome in exactly one place.

(d) All strings over {a,b} such that every prefix has at least as many a's as b's.

(e) All strings over {a,b} that end with a.

(f) All strings over {a,b} that end with a.