Question $2(5$ points$)$

Assume that initially $\backslash (\backslash$mathrm$\{$A$\}=5\backslash )$ and $\backslash (\backslash$mathrm$\{$B$\}=10\backslash )$ are values on hard disk. The following is a transaction T$1$ of user program on A and B $(->$ denotes assignment, $\text{'}$;$\text{'}$ gives order of operations$)$:

T$1$: A$+$B $->$ A; A$+$B $->$ B

T$1$ generates the following actions $($read$/$write$/$output$)$ to the database:

T$1$: Read$($A$,$ t$)$; Read$($B$,$ u$)$; t$+$u $->$ t; Write$($A$,$ t$)$; t$+$u $->$ u; Write$($B$,$ u$)$; Output$($A$)$; Output$($B$)$;

and the following undo$/$redo log records:

; ; ;

For the following transaction T$3,$

T$3$: B$+1->$ A; A$+1->$ B

$1.$ Add necessary read$/$write$/$output actions to the computation;

$2.$ Show the undo$/$redo log records it generates.