By default this term adds one network statistic to the model for each pair of nodes of mode two. It is equal to the number of (first mode) mutual partners of that pair. The first mode of a bipartite network object is sometimes known as the "actor" mode and the seconds as the "event" mode. So this is the number of actors going to both events in the pair. This term can only be used with undirected bipartite networks.
# binary: coincidence(levels=NULL,active=0)specifies which pairs of nodes in mode two to include. (See Specifying Vertex
attributes and Levels (?nodal_attributes) for details.)
selects pairs for which the observed count is at least active . Ignored if levels is
specified. (Thus, indices passed as levels should correspond to indices when levels = NULL and active = 0.)
ergmTerm for index of model terms currently visible to the package.
ergm:::.formatTermKeywords("ergmTerm", "coincidence", "subsection")