This is a question from the exam of our "Automata and Formal Languages" course. There is a question where asked to prove or disprove that any "relative complement" operation between two context sensitive languages will also produce a context sensitive language.
I have spent too much time on finding the formal prove of those statements. Where / How can I find the proofs? Or how to prove them by myself? Can anyone point me to a reference ? Can any one post here the proofs ?