(a) Determine a regular expression for the language L over the alphabet {a,b} that consists of all words that have at least one b but contain exactly one aa substring (and no other as). Example of words in the language are aab,bbbaabbb, bbbbbaabbbbbbbbb etc. Examples of words that are not in the language are a, aba,bbab, aaabbbb, baabbbbaabb etc. (b) Design a deterministic finite automaton (DFA) that will recognise all of the words in L as defined above. (c) Use Theorem 21 to develop a context-free grammar (CFG) for the language L. (d) Convert the following CFG to Chomsky Normal Form (CNF): SaXY/YbXXZYZ/aYbY/Za/