$2-$ Consider the schedules S$4,$ S$5,$ and S$6$ below. State whether each schedule is conflict$-$serializable and view$-$serializable. Draw the precedence graph and show the related data items on arrows. You can simply give a single example of why they are not serializable $($you do not need to draw the whole precedence graph$).$ If it is view$-$serializable, show the equivalent serial schedule$($s$).$ Explain your reasons by referring to the lecture notes.

$-$ S$4$: W$1($B$)$; W$3($A$)$; W$1($D$)$; R$1($B$)$; R$2($C$)$; R$1($A$)$; R$2($B$)$; R$3($A$)$; R$2($C$)$; R$1($C$)$; C$3$; C$1$; C$2$;

$-$ S$5$: R$4($C$)$; R$1($B$)$; R$4($B$)$; R$3($C$)$; R$4($A$)$; R$4($D$)$; R$1($C$)$; W$1($C$)$; R$2($D$)$; W$3($D$)$; W$3($B$)$; R$2($A$)$; W$1($B$)$; R$1($A$)$; C$3$; C$4$; C$1$; C$2$;

$-$ S$6$: R$3($B$)$; W$2($C$)$; R$4($B$)$; W$1($D$)$; R$2($C$)$; R$3($A$)$; W$4($D$)$; W$4($C$)$; R$3($C$)$; R$1($B$)$; R$2($B$)$; C$2$; R$1($B$)$; R$4($A$)$; R$3($C$)$; R$1($B$)$; C$3$; C$4$; C$1$;