- RW, WW, WW conflicts yield ordering constraints.
- Serializability requires consistency among these constraints -- no cycles.
- A lock held to the end of the transaction says:
- I (T1) depend on this value.
- You (T2) can have it once I'm done.
- T1 < T2.
- Lock on X held by T1 means T1 < any transaction that wants X also.