Chapter 26.2, Problem 1E

Program Plan Intro

To prove that the summation of $|f\uparrow f\text{'}|$ is equals to ${\displaystyle \sum _{v\in V1}(f\uparrow f\text{'})(s,v)}+{\displaystyle \sum _{v\in V2}(f\uparrow f\text{'})(v,s)}$ .