Strategic vertex labeling

Question

We are given a graph $G=(V,E)$ with positive edge weights $w_{i}$ and numerical {0,1,-1} labels $l$ for all vertices . We know that $G$ has a subset $G'$ with all vertices labeled 0. The problem is to assign labels to the vertices in $G'$ in such way that this sum is maximized $\sum_{e_{u,v}\in E} w_{i}l_ul_v.$ The question is whether this problem is NP-complete or not. If it is not then what is the polynomial algorithm?

Personally I believe that this problem is essentially a form of 3-Coloring. The challenge is to chose the labels {1,-1} depending on the neighbors. Say the boundary between $G$ and $G'$ has a lot of 1s then it is better to chose 1s for the labeling of vertices in $G'$, similarly if the boundary has lots of -1s then it is better to chose -1s for labeling because $-1*-1=1$. So essentially this becomes some sort of reverse 3-Coloring problem where the neighbors have to have matched color.

Can you help reduce this problem to 3-Coloring (or vice-versa) ? Or perhaps there is polynomial time algorithm ?

Answer 1

Hint: Your problem looks a lot like minimum $(s,t)$-cut.