Write a recursive definition for each of the following:

c) Reverse of a word such as define on any alphabet such as . We represent the reverse of with , which is the symbols of written in the reverse order.

Example: = =

d) The set of strings on any alphabet such as , which are palindrome. Palindrome strings are read the same forward and backward.

e) The set of strings, which has the same number of as and bs on = {a, b}.