Bipartite Network Projection

A bipartite graph connects two disjoint node sets (e.g., papers and authors). One-mode projection onto authors creates weighted co-authorship: edge weight = shared papers. Nestedness measures hierarchical structure.

Edges (bip): — Density: — Proj edges: — NODF nestedness: —

Top nodes (A)10

Bottom nodes (B)8

Link probability0.30

Project onto

Layout

Given bipartite matrix M_ij, the one-mode projection weight is W_ij = Σ_k M_ik·M_jk (shared neighbors). In ecology, this is how to analyze plant-pollinator networks. The NODF nestedness metric (Almeida-Neto 2008) measures whether specialists interact with subsets of generalists' partners — a signature of mutualistic coevolution.