Let L = {ab | n ≥ 0}. The complement of this language is the language L'.
For example,
Ip3 Ipqp aabb + L aaabbb L'
Iqpn baab EL ababeL
Give a context-free grammar generating L.
Hint: There are four separate cases you need to consider. You might want to design the grammar to consider each of these four cases independently of one another.