is the graph theoretic expression of the fact that two entities, represented by nodes, are directly related, tied, or connected with one another. Formally, given entities i and j in a set of agents , and the ={ aij} arc s denoting the existence of relations from i to j; i and j are adjacent if there exist either of the two arcs, aij or aji. Given the digraph = (,), its adjacency matrix () is defined by () = { ij} where ij=1 if either aij or aji exists, and 0 otherwise. density Criterion: a procedure for tie assignment in the construction of a blockmodel. According to this criterion, an arc ( AB) between two blocks (A,B) for a given relation is 1 if the observed density of arcs between the two blocks ( AB) is at least as large as , and zero otherwise. Often, is chosen to equal (), the density of the original sociomatrix. Formally, for = ; AB = 1 if AB ³ else AB = 0.
Domains, including product and service platforms, that adjoin existing customer bases and product lines but don't entirely include them. These platforms leverage some, but not all, existing business systems. Adjacent extensions of existing lines bring existing business systems into new industries (customer bases and product types). Variable by degree in the sense that some capability adaptation often is required even in extensions; more significant changes in capability are required in new platform growth.