Figure 2. The influence of current status on the formation of new links in the Flickr and Epinions (in the insets) networks.

(a)–(d) The cumulative functions of relative probability, κ^f (k_f), κ^f (k_out), κ^f (k_in), and κⁱⁿ(k_in), respectively, characterizing the cross correlations in the growth of degrees. For example, in (b), κ^f (k_out) plots the cumulative probability for a user to build a new cross link given that his existing outdegree is k_out. The exponents are obtained by fitting the curves averaged over different initial t₀, and Δt is one day. See the text for the definitions of the triadic and non-triadic links. (e)–(f) Characterizing the localized influence among neighboring users. (e) The cumulative functions of probability for a user to build a cross link to a specific photo (review) given that u of his neighbors have already favorite-marked (commented) it. (f) The cumulative functions of relative probability for a pair of users to build a social link given that they have already shared z favorite photos (reviews). The straight lines are guide to the eye through this paper.