Fig. 1. Hypergraph affinity and ratio scores for a small hypergraph.

(A) An example of a set of size 3 group interactions between two classes, modeled by a small hypergraph. Each triangle in the figure indicates a three-way group interaction, and color indicates node class (green or blue). (B) Degrees, affinity scores, and baseline scores for the hypergraph. A node’s type-t degree is the number of groups it belongs to in which exactly t nodes are from its class. The type-t degree for an entire class is the sum of type-t degrees across all nodes in the class (Σ columns in the table). The type-t affinity for a class X, denoted by h_t(X), is the ratio between the class’s type-t degree and its total degree (the sum of type-t degrees for all t). The type-t baseline score b_t(X) is the probability that a node joins a type-t group if other nodes are selected uniformly at random. (C) The ratios of affinity to baseline (ratio scores) summarize the overall group participation rates for both types of nodes.