bipartite
count; should the network be interpreted as bipartite? If present (i.e., non-NULL) it is the count of the number of actors in the first mode of the bipartite network. In this case, the overall number of vertices is equal to the number of 'actors' (first mode) plus the number of `events' (second mode), with the vertex.ids of all actors preceeding all events. The edges are then interpreted as nondirected.