(Solved): Q3. [2 points] A useless state in pushdown automaton is never entered on any input string. Consider ...

Q3. [2 points] A useless state in pushdown automaton is never entered on any input string. Consider the problem of determining whether a pushdown automaton has any useless states. Formulate this problem as a language and show that it is decidable. (Hint: Use Theorem 4.8.)