Problem 4 (110 points). Consider the following CFG with the eight terminals: true, false, A, V, !, ==, (, and ). erpr true false exprerprerpr Verpr | !erpr | expr == expr (erpr) Indeed, the starting symbol is erpr. Let's call this grammar G. This grammar is ambiguous, i.e., there exist at least two parse trees for some expression. For example, consider the following expression: !true false Vtrue == true (a) Give two different derivations for this expression such that the corresponding parse trees are differ- ent from each other. (10 points) (b) Give the corresponding parse trees for each derivation in the previous question. (10 points) (c) Give the corresponding two ASTs. (10 points) (Hint: Note that operators A, V, ==, and ! can appear as interior nodes in ASTI. You may remove the nonterminal erpr from ASTs as it does not convey any computational information.) (d) If you pass the ASTs from the previous question to an evaluator, what would be the final value in each case? (10 points)