Let

$$

$$be a directed graph on

$$

$$vertices$.$ If the associated undirected graph for

$$

$$is

$$

$$

$,$

$$prove that

$$

v

i

n

V

$($

$$

$$

$($

$$

$)$

$2$

$)$

$=$

$$

v

i

n

V

$($

$$

$$

$($

$$

$)$

$2$

$)$

$.$