Figure 3. The role of PWCS on the probability of f₁₂₃.

Node 2 (blue color, call introducer) wants to introduce node 1 (green color, call nominee) to node 3 (red color, call acceptor). The number common neighbor between node 2 and node 3 in (a–c) is 0, 1 and 2, respectively. According to Eq. (4), one has (a) f₁₂₃ = 1/3; (b) f₁₂₃ = 1/2; (c) f₁₂₃ = 1. Namely, the probability of node 1 being introduced to node 3 in (c) is larger than (b) and is further larger than in (a).