Rich-Club Network Phenomenon

Degree correlations & hub interconnectivity

Network Parameters

Rich-club coefficient:
φ(k) = E_>k / [N_>k(N_>k-1)/2]

Fraction of edges among nodes with degree > k, normalized by maximum possible.

Normalized φ_norm(k) = φ(k) / φ_rand(k)
> 1: rich-club ordering present

Hub nodes (gold) form a dense interconnected core.