The Wiener index W, denoted w and also known as the "path number" or Wiener number (Plavšić et al. 1993), is a graph index defined for a graph on n nodes by W = 1/2 sum_(i = 1)^n sum_(j = 1)^n (d)_(i j), where (d)_(i j) is the graph distance matrix. Unless otherwise stated, hydrogen atoms are usually ignored in the computation of such indices as organic chemists usually do when they write a benzene ring as a hexagon.

average disorder number | Balaban index | graph distance matrix | Kirchhoff index | resistance distance | topological index | Wiener sum index