Problem 7 Let A and B be recognizable languages such that AUB= 2*. Show there exists a decidable language C such that BCC CA. (Hint: review Theorem 4.22. Look for a a TM that accepts every string in A-B, rejects every string in B A, and it may either accept or reject the strings in An B.) Problem 7 Let A and B be recognizable languages such that AUB= 2*. Show there exists a decidable language C such that BCC CA. (Hint: review Theorem 4.22. Look for a a TM that accepts every string in A-B, rejects every string in B A, and it may either accept or reject the strings in An B.)