ABSTRACT
The Wiener index is commonly considered as the most classic and widely used distance-based index in chemical graph theory. It is named after the chemist Harry Wiener, who proposed this concept (originally calling it the path number) in 1947 [118, 119]. Given a graph G, the Wiener index of G is defined as
W (G) = ∑
{u,v}⊆V (G) d(u, v),
where d(u, v) is the distance between vertices u and v in G. For example, in Figure 2.1, we have a graph on 6 vertices, the
) = 15
distances between pairs of vertices are
1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2.
