The Wiener index of signed graphs

The Wiener index of a graph W(G) is well studied topological for graphs. An outstanding problem Šoltés to find graphs G such that W(G)=W(G−v) all vertices v∈V(G), with the only known example being G=C11. We relax this by defining notion indices signed graphs, which we denote Wσ(G), and under relaxation construct many Wσ(G)=Wσ(G−v) v∈V(G). This ends up related independent interest, asks when it possible 2-color edges there path between any two uses each color same number times. briefly explore latter problem, as its natural extension r-colorings.