Let = {a, b} for part a, b and c only.

a) Give a regular expression for the set of all elements of containing exactly two bs or exactly two as.

b) Give a regular expression for the set of all elements of beginning and ending with a and containing at least one b.

c) Give a regular expression for the set of all elements of such that the number of as in each string is divisible by 3 or the number of bs is divisible by 5. Find regular expressions corresponding to the following sets:

d) {abcd, abcbcd, abcbcbcd, abcbcbcbcd, . . .} e) {abcd, abef, cdcd, cdef }. f) Convert following regular expression to the -NFA. (bba)(ab+bc)*(b+c)