8. The following transactions execute under a optimistic concurrency control:

T1: ReadSet:{B, E}, WriteSet: {C, E, F } T2: ReadSet: {F}, WriteSet: {A,B} T3: ReadSet: {A}, WriteSet:{C}

T4: ReadSet: {A,C}, WriteSet: {B,D}

T5: ReadSet: {F }, WriteSet: {C, D} Consider the following sequence of events:

1. T1 initiates Read phase 2. T2 initiates Read phase 3. T2 initiates Validation phase 4. T1 initiates Validation phase 5. T3 initiates Read phase 6. T2 completes Validation phase 7. T4 initiates Read phase 8. T5 initiates Read phase 9. T4 initiates Validation phase

10. T1 completes Validation phase 11. T5 Initiates Validation Phase 12. T3 Initiates Validation Phase 13. T4 completes Validation phase 14. T3 completes Validation phase 15. T5 completes Validation phase

Assume that for each transaction the Read phase ends exactly before the beginning of the validation phase of that transaction. For instance, 4 T1 initiates Validation phase implicitly means that T1 completes the Read phase before this event and after the previous event (event #3). And for each transaction the Write phase is completed immediately after the completion of the validation phase of that transaction (if the validations is successful). For instance, 10 T1 completes Valida- tion phase implicitly means that T1 completes the Write phase immediately after completing the Validation phase of T1 and before the beginning of the next event (event #11).

Which of these five transactions (T1, T2, T3, T4 and T5) validate successfully? For the transactions failed to validate explain the reason.