s1: True: conflict serializable to schedule >> $T_{1}\rightarrow$$T_{2}\rightarrow T_{3}$
S2: True: allowed in basic 2PL.
s3: False
strict recoverable schedule>> if transaction $T_{i}$ updates the data item A, then any other transaction $T_{j}$ not allowed to R(A) or W(A) until commit or rollback of $T_{i}$.
| $T_{i}$ |
$T_{j}$ |
| W(A) |
|
| ..... |
|
| commit or rollback |
|
| |
R(A) or W(A) |
s4: False>>> strict 2PL is basic 2PL in which all exclusive locks should be hold until commit or rollback
but here R$_{2}$(B) request for shared lock on B and B is already locked(xclusive) by $T_{1}$.
