Consider regular expressions over {a, b} that use e to denote the language containing only the empty string. Such an expression is a string over the alphabet {a, b, , , , , (, )}.

Give an unambiguous context-free grammar that generates the language of regular expressions that contain no redundant parentheses.

Give an unambiguous context-free grammar that generates the language of regular expressions that contain no redundant parentheses. Derivation trees should reflect normal operator prece- dence. Repetitions of the associative operations (union and concatenationshould not have parentheses, but no other simplifications should be performed. For example, r UrUr is valid, but neither (r Ur) Ur nor r U (r Ur) is. p** is allowed, but not (r*)* Explain why your grammar is correct and unambiguous. (Formal proof not required.)