2PL Conflict-Serialisability Proof
See Locking Conflict-Serialisable Schedules for how two phase locking works.
If $S$ is a schedule containing only 2PL transactions, then $S$ is conflict-serialisable.
Claim: We can move all operation of $T_i$ to the beginning of the schedule (using swaps of consecutive non-conflicting operations).
No formal definition is given in this proof so it is better to watch the video (proof starts at 1:33).