QUESTION 4: (33 Points) Two concurrent transactions, TI and T2, consist of the following: T1: rl(x); rl(z); wl(x); T2: 12(z); 12(y); w2(z); w2(y);12(u) where ri(x) and wi(x) denote a read and a write operation by transaction i on data item x. Data items x, y and v are stored at site A, while z and u are stored at site B. In addition, two local transactions L3 and L4 consist of the following: L3: 13(x); 13(y); w3(y); 13(v) at site A L4: 14(z), w4(z), r4(u) at site B and they are executed concurrently with TI and T2