Consider the transactions $T1, T2, \:\text{and} \:T3$ and the schedules $S1 \:\text{and} \:S2$ given below.
- $T1: r1(X); r1(Z); w1(X); w1(Z) $
- $T2: r2(Y); r2(Z); w2(Z) $
- $T3: r3(Y); r3(X); w3(Y) $
- $S1: r1(X); r3(Y); r3(X); r2(Y); r2(Z); w3(Y); w2(Z); r1(Z); w1(X); w1(Z) $
- $S2: r1(X); r3(Y); r2(Y); r3(X); r1(Z); r2(Z); w3(Y); w1(X); w2(Z); w1(Z) $
Which one of the following statements about the schedules is TRUE?
- Only $S1$ is conflict-serializable.
- Only $S2$ is conflict-serializable.
- Both $S1$ and $S2$ are conflict-serializable.
- Neither $S1$ nor $S2$ is conflict-serializable.