Consider the problem of scheduling four tasks: V$1,$ V$2,$ V$3,$ V$4,$ each of which takes one hour to complete. The tasks may start at $1$:$00,2$:$00,3$:$00.$ Any number of tasks can be executed simultaneously provided the following restrictions are satisfied. V$1$ must start after V$3($i$.$e V$1>$V$3).$ V$3$ must start before D $($i$.$e V$3<$ V$4).$ Vi cannot execute at the same time as V$2($i$.$e V$1$#V$2).$ V$2$ cannot execute at the same time as V$4($i$.$e V$2$#V$4).$ V$4$ cannot start at $2$:$00($i$.$e V$4+2).$a$)$ Formulate the problem as a CSP by stating: the variables, their domain, and the applicable constraints. $($Hints: focus on the start time of a task$).(1$ pointb$)$ Draw the constraint network. $(2$ points$]$c$)$ Apply arc$-$consistency to each constraint in the CSP until no values can be ruled out $($i$.$e$.,$ the CSP becomes arc$-$consistent$).[2$ points$]$