Figure $22\mathrm{.}6$ shows the log corresponding to a particular schedule at the point

of a system crash for four transactions T$1,$ T$2,$ T$3,$ and T$4.$ Suppose that we

use the immediate update protocol with checkpointing. Describe the recovery process from the system crash. Specify which transactions are rolled

back, which operations in the log are redone and which $($if any$)$ are undone,

and whether any cascading rollback takes place.