“…which sums over all unique values of degree k j among the individual's friends N (i), and p(k) is the non-zero fraction of the individual's friends with degree k. Considering the large space of possible values k j could take (usually varying from several to hundreds), it is less likely that two friends collide with the same degree, and, therefore, any possible value of friend degree gets an even probability, making balance diversity a trivial inverse of variety diversity. For example, say both users A and B have 5 friends, whose degrees are [6,7,8,9,10] and [1,10,20,30,40], respectively. Equation (1) gives H A = H B = 2.322, while user A is believed intuitively to be less diverse because his friends have similar degrees.…”