Stochastic Block Model — Planted Partition Detectability

Intra p (a/n): 0.20 Inter q (b/n): 0.05 n nodes: 60 Regenerate graph

Planted partition SBM with 2 equal communities. Detectability threshold: (a−b)² = 2(a+b). Below threshold, no algorithm can find communities better than chance. Nodes colored by true community; layout separates them visually.