Structural cohesion
In sociology, structural cohesion is the conception of a useful formal definition and measure of cohesion in social groups. It is defined as the minimal number of actors in a social network that need to be removed to disconnect the group. It is thus identical to the question of the node connectivity of a given graph in discrete mathematics. The vertex-cut version of Menger's theorem also proves that the disconnection number is equivalent to a maximally sized group with a network in which every pair of persons has at least this number of separate paths between them. It is also useful to know that -cohesive graphs are always a subgraph of a -core, although a -core is not always -cohesive. A -core is simply a subgraph in which all nodes have at least neighbors but it need not even be connected.
The boundaries of structural endogamy in a kinship group are a special case of structural cohesion.