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1)    here is no cycle in dependency graph so it is conflict serializable 

2)   it is 2pl see the graph shared lock taken on A in T1 before releasing the X lock of B and C

3) strict recoverable  means if someone write the data other can read and write after commit of that transaction

 

here $W_{1}\left ( B \right )$ and $R_{3}\left ( B \right )$ making it not strict

4)     it not strict 2pl because the X lock of B and C in T1 should be release after T1 commit    

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2 votes
2 votes
What I think Is Since no cycle is formed it should be Conflict serialazable

Now for 2PL we should see that every transaction should get the required shared and exclusive lock in best case but here we cannot give the required lock to all of them without overlapping So,2PL fails here...

It is Recoverable schedule but not Strict

Am I correct????
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S1: TRUE. Because precedence graph is acyclic.

S2: TRUE. Allowed by 2PL.

T1 T2 T3
  S(A)  
   R(A)  
X(B)    
W(B)    
X(C)    
W(B)    
S(B)    
U(B)    
U(C)    
    S(B)
    R(B)
  S(B)  
  R(B)  
R(A)    
U(A)    
  S(C)  
  R(C)  
  U(C)  
  U(B)  
    X(A)
    W(A)

S3: FALSE.  Because following should be condition.

T1 T2
   W(A)  
   COMMIT  
    R(A)/W(A)

S4: False. Not allowed by strict 2PL

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